0
OUR OCEAN PLANET
OUR OCEAN PLANET
SECTION 5 – TROPICAL SEAS
1
REVISION HISTORY
Date
Version
Revised By
Description
Aug 25, 2010
0.0
VL
Original
5. TROPICAL SEAS
5. TROPICAL SEAS
2
5. TROPICAL SEAS
Tropical seas are warm, clear, sunlit seas that girdle the Equator
between the Tropic of Cancer and Tropic of Capricorn. Several key
habitats are found in tropical seas, namely:
1. Mangroves
The mangrove habitat plays an important role in tropical and
subtropical regions of the world. Different mangrove plant species
protect and stabilize low lying coastal land, and provide protection
and food sources for estuarine and coastal fishery food chains.
Mangroves also serve as feeding, breeding and nursery grounds for
a variety of fish, crustaceans, molluscs, reptiles, birds and other
wildlife.
2. Sea Grass
Sea grass beds are highly diverse and productive habitats that are
home to hundreds of species of animals and plants including
juvenile and adult fish, epiphytic and free-living macro-algae and
micro-algae, bristle worms, nematodes, crustaceans, molluscs and
reptiles.
3. Coral Reefs
Coral reefs are warm, clear, shallow ocean habitats that are rich in
life. The coral provides shelter for many animals including sponges,
fish, jellyfish, anemones, sea stars, crustaceans, molluscs, sea
turtles and sea snakes.
3
5. TROPICAL SEAS
4
5.1 MANGROVES
5.1 MANGROVES
5
5.1 MANGROVES
5.1 MAGROVES
5.1.1 Mangroves
Mangroves forests are tropical, tidal salt-marsh forests dominated by
mangrove trees and shrubs that have roots which are exposed at
low tide. Mangroves are flowering trees that are tolerant to salty or
brackish (mixed fresh and salt) water. They are found in coastal
environments and salty mud flats near the shoreline where fine
sediments, often with high organic content, collect in areas protected
from high energy wave action.
TYPES OF MANGROVE
In Florida and the Caribbean, there are four types of mangrove:
1. Red Mangrove
Red mangroves have long prop roots that reach down into the water.
These roots serve as a nursery area for many coral reef fish and
invertebrates. Most fish caught by fishermen on reefs need this
habitat to mature, safe from predators and with a good food supply.
The roots also protect the shoreline from wave erosion during
storms. They also filter sediment from runoff coming off the land.
Red mangrove wood is heavy and durable. The bark is used for
tanning and medicinal purpose while the bark, leaves and shoots
yield various dyes.
6
5.1 MANGROVES
2. Black Mangrove
Black mangrove grows behind the red, in saturated soil where the
trees breathe using roots called “pneumatophores” that project out of
the soil. The leaves of the black mangrove are long and narrow.
Excess salt is excreted through the leaves, where it can be seen
crystallized on the leaves.
3. White Mangrove
White mangroves can be found further inland, in moist sandy areas
of lower salinity (salt content). Like the black mangrove, they also
have the ability to excrete excess salt through tiny pores located at
the base of each leaf.
4. Buttonwood Mangrove
The Buttonwood mangrove is generally found furthest inland and
has the largest leaves of them all.
7
5.1 MANGROVES
8
IMPORTANCE OF MANGROVES
Mangroves are important for several reasons:
(a) Nurseries
Mangroves serve as feeding, breeding, and nursery grounds for a variety of fish, molluscs, birds, and
other wildlife. Mangroves also produce a large amount of leaf litter per year which benefits estuarine
food chains. In south Florida, an estimated 75% of the game fish and 90% of the commercial species
depend on the mangrove system.
(b) Preventing Erosion
Mangrove roots are important in preventing erosion and the washing away of land into the ocean.
Interesting!
Mangroves have several adaptations that allow them to survive in an inhospitable environment. Black and white
mangroves have special roots that grow vertically above the ground and act like snorkels. These roots allow the
tree to absorb oxygen from the air when the ground is covered with salt water and the soil is low on oxygen.
Black mangroves also excrete excess salt out through their leaves which can often be seen as salt crystals on
the leaves. Red mangroves are the best adapted for living in salt water and can usually be found nearest the
sea, often actually growing in the water. The roots of red mangroves resemble stilts and they allow the tree to
stand in the water. They reproduce through large seeds called “propagules”, which look like darts, hanging from
the ends of their branches. Each propagule is a small plant with roots already growing on it. When a propagule
falls from the parent tree, it can grow directly in the muddy sediment or it can float along until the root end
weighs it down into the correct position for it to grow.
5.1 MANGROVES
5.1.2 Mangrove Life
9
5.1 MANGROVES
RED MANGROVE
The red mangrove (Rhizophora mangle) is a tall tree that reaches
21-24 m (70-80 ft) in height in the tropics. In Florida, however, it is
characterized as a short bushy tree reaching about 6 m (20 ft) in
height. It is characterized by its numerous above ground roots
called prop roots. The red mangrove grows in brackish areas along
creeks, bays, and lagoons.
MUDSKIPPER
A mudskipper is a fish found in tropical coastal regions of Africa and
Asia that is able to move on land on strong pectoral fins and breathe
air. Mudskippers are uniquely adapted to an amphibious lifestyle
and can breathe through their skin and the lining of their mouth and
throat. However, this is only possible when the mudskipper is wet,
limiting mudskippers to humid habitats and requiring that they keep
themselves moist. Mudskippers are found in tropical and subtropical
regions of the Indo-Pacific and the Atlantic coast of Africa, and are
quite active when out of water feeding and interacting with one
another, for example, to defend their territories.
10
5.1 MANGROVES
ALLIGATORS, CAIMANS, CROCODILES & GHARIALS
Alligators are found in the southern United States and eastern
China. Caimans are found in Central America and South America.
Crocodiles are found in Mexico, Central and South America, Africa,
Southeast Asia and Australia. They live in grassy swamps and
slow-moving rivers. Gharials live in Indian rivers with deep pools
and sand or mud banks, and eat fish.
All crocodilians are carnivores and eat whatever they can catch in
the water or along the banks, including fish, turtles, frogs, birds, pigs,
deer, buffalo, and monkeys, depending on the size of the animal.
The crocodilians don't chew their food; they tear bite-sized pieces off
a carcass or swallow small prey whole.
The saltwater crocodile (Crocodylus porosus) is the world's largest
reptile. These amazing creatures are found on the northern coast of
Australia and inland for up to 100 km (62 miles) or more. Saltwater
crocodiles grow to lengths of 7 m (23 ft) but the average size of is 4
m (12 ft) long.
11
5.1 MANGROVES
12
REFERENCES & FURTHER READING
http://www.sfrc.ufl.edu/4H/Other_Resources/Contest/Highlighted_Ecosystem/Mangrove%20Forests.htm
- Florida's Mangrove Forest Ecosystem
http://www.nationaltrust.org.ky/info/mangroves.html - Mangroves
http://www.nationaltrust.org.ky/info/centralmangrove.html - Mangroves of Cayman Islands
http://mangrove.nus.edu.sg/guidebooks/contents.htm - Mangroves of Singapore
http://www.sfrc.ufl.edu/4h/Red_mangrove/redmangr.htm - Red mangrove
http://www.epa.gov/owow/wetlands/types/mangrove.html - Mangroves
http://www.stx.k12.vi/torch99/fldtrp/mangrove.htm - Mangroves
http://www.enchantedlearning.com/subjects/mammals/manatee/ - Manatees
http://www.sandiegozoo.org/animalbytes/t-crocodile.html - Crocodilians
http://www.flmnh.ufl.edu/cnhc/csl.html - Crocodile species
Byatt, Andrew, Fothergill, Alastair and Holmes, Martha, The Blue Planet: Seas of Life, Chapter 3, DK
Publishing Inc., (2001), ISBN 0-7894-8265-7
5.2 SEA GRASSES
5.2 SEA GRASSES
13
14
5.2 SEA GRASSES
5.2 SEA GRASSES
5.2.1 Sea Grasses
Sea grasses are flowering plants that live and grow in the marine
environment. There are about 60 species worldwide and they are
from one of four plant families as follows:
Family Posidoniaceae
 Posidonia
Family Zosteraceae
 Zostera (Eelgrass)
 Heterozostera
 Phyllospadix
Family Hydrocharitaceae (Frogbit family)
 Enhalus
 Halophila
 Thalassia (Turtle Grass)
Family Cymodoceaceae
 Amphibolis
 Cymodocea
 Halodule
 Syringodium
 Thalassodendron
SEA GRASS
5.2 SEA GRASSES
15
Sea grasses are plants so they must photosynthesize to survive and must grow in the photic (light
penetrating) zone of the ocean. Most sea grasses are found in shallow and sheltered coastal waters
anchored in sand or mud bottoms. They undergo pollination while submerged and complete their entire
life cycle underwater.
Sea grasses form extensive beds that can be either mono-specific (made up of just one species) or
multi-specific (where more than one species co-exist). Tropical sea grass beds can be diverse (e.g. 13
species recorded in the Philippines). In temperate areas, however, usually one or just a few species
dominate (e.g. Common Eelgrass (Zostera marina) in the North Atlantic).
Sea grass beds are highly diverse and productive ecosystems and can harbor hundreds of species
including juvenile and adult fish, epiphytic and free-living macroalgae and microalgae, bristle worms, and
nematodes, crustaceans and molluscs. Sea grass herbivory is a highly important link in the food chain
with hundreds of species feeding on sea grasses including dugongs, manatees, fish, geese, swans, sea
urchins and crabs.
Sea grasses are sometimes labeled ecosystem engineers because they partly create their own habitat –
their leaves slow down water-currents increasing sedimentation and the sea grass roots and rhizomes
stabilize the seabed. Their importance is mainly due to their provisioning of shelter to associated
species (through their three-dimensional structure in the water column) and for their extraordinarily high
rate of primary production. Sea grass areas are important fishing grounds, wave protection, oxygen
production, and protection against coastal erosion.
5.2 SEA GRASSES
5.2.2 Sea Grass Life
16
17
5.2 SEA GRASSES
SEA GRASS
One type of sea grass – turtle grass – is characterized by its flat,
strap-like blades. Blades can be 76 cm (30 in) tall and 4.0 cm (1.5
in) wide. There are 9-15 parallel veins per blade. Rhizomes are
thick and tough, with an extensive root system that anchors the
rhizomes to the substrate. Scaly flowers, generally whitish-green to
pink in colour, are produced. Fruits are rounded and pod-like.
Turtle grass grows in the sub-tidal zone from approximately the low
tide line to depths of 9 m (30 ft) or more. In clear waters, depth can
be up to 27 m (90 ft). Sheltered areas having muddy substrates are
prime habitat. Turtle grass ranges throughout the tropical western
Atlantic from east central Florida south through the Gulf of Mexico,
Central and South America to Venezuela.
SEA TURTLE
Sea turtles are large air-breathing reptiles with paddle-shaped foreflippers and a number of other adaptations that make them perfectly
at home in the ocean. Today, only seven species remain worldwide
– green, loggerhead, hawksbill, flatback, Kemp’s ridley, olive ridley,
and leatherback turtle. Although they may live their entire life at sea,
sea turtles must return to the land to nest. Under cover of darkness,
a female will drag her body across a sandy beach where she will dig
a nest and deposit about 100 eggs in the warm sand. After about 60
days of incubation, the eggs will hatch and the hatchlings will make
their way back to the sea.
SEA GRASS
5.2 SEA GRASSES
SPOTTED EAGLE RAY
Spotted Eagle rays have dark grey to brown bodies with a pattern of
white spots and streaks above and are whitish below. They also
have long graceful “wings” (pectoral fins) that can reach 2.4m (8 ft)
across and a long whip-like tail with a long spine near base. They
can be found in sea grass, on coral reefs, or in the open sea in large
schools during non-breeding season.
MANATEES & DUGONGS
Manatees belong to the Sirenian family which includes the
Amazonian manatee and the African dugong. The average adult
manatee grows to be about 3.6 m (12 ft) long and weighs about 800
kg (1,800 lbs). When manatees are newborn, their skin is greyblack which lightens to grey as they mature. Manatees breathe air
and can stay underwater for up to 20 minutes although surfacing
every 5 minutes is more usual. Their nostrils are covered by flaps
that close during dives. A manatee's life span is roughly 60 years.
Manatees live in warm, shallow waters along coasts, in estuaries,
and canals. They can live in salt, fresh or brackish waters.
Manatees are found along the Gulf Coast of the USA (wintering in
Florida) and in many waterways in South America. Manatees are
endangered and their numbers are dwindling.
18
5.2 SEA GRASSES
Dugongs are closely related. Dugongs are large grey mammals with
nostrils near the top of their snouts and bristles near their mouths.
They have two flippers, each of which has three to four nails, and
they have no hind limbs. Fully grown, they may be 3 m (10 ft) long
and weigh 400 kg (882 lbs). Dugongs swim by moving their broad
fluke-like tail in an up and down motion and using their two foreflippers. Dugongs are highly migratory. In Australia, dugongs swim
in the shallow coastal waters of northern Australia. They are also
found in other parts of the Indian and Pacific Oceans in warm
shallow seas where sea grass is found. They surface only to breathe
and never come on to land. Female dugongs give birth underwater
to a single calf at 3 to 7 year intervals. The calf stays with its
mother, drinking milk from her teats and following close by until 1 or
2 years of age. Dugongs reach adult size between 9 and 17 years
of age. Dugongs are sometimes called “sea cows” because they
graze on sea grasses. Dugongs are slow-moving and have few
defenses against predators but, because they are large animals,
only large sharks, saltwater crocodiles and killer whales are a
danger.
REFERENCES & FURTHER READING
http://www.seagrasswatch.org/home.html - Sea grass monitoring
http://www.abc.net.au/oceans/jewel/grass/default.htm - Sea grass
http://sanctuaries.noaa.gov/welcome.html - National Marine Sanctuaries
http://www.environment.gov.au/coasts/species/dugongs/index.html - Dugongs
19
5.3 CORAL REEFS
5.3 CORAL REEFS
20
5.3 CORAL REEFS
5.3 CORAL REEFS
5.3.1 Coral Reefs
Coral reefs are warm, clear, shallow ocean habitats that are rich in
life. The reef's massive structure is formed by coral polyps –
colonies of tiny, invertebrate animals (cnidarians). Each coral polyp
secretes a hard calcium carbonate (limestone) cup around itself.
These cups are fused with cups from other members of the colony to
form large boulder, branching and platy shaped rock-like structures.
When an individual coral polyp dies, it leaves behind its skeletal cup.
A coral reef provides shelter for many animals including sponges,
sea stars, crustaceans, molluscs, fish and sea turtles.
TYPES OF REEF
Coral reefs form when free-swimming coral larvae attach to the
submerged edges of islands, continents, or hard substrate. As the
corals grow and expand, reefs take on one of three major
characteristic structures — fringing, barrier or atoll.
1. Fringing reefs – fringing reefs, which are the most common,
project seaward directly from the shore, forming borders along the
shoreline and surrounding islands. They grow on the continental
shelf or around islands in shallow water.
21
5.3 CORAL REEFS
2. Barrier reefs – barrier reefs also grow parallel to shorelines but
are further out and usually separated from the land by a deep
lagoon. They are called barrier reefs because they form a barrier
between the lagoon and the seas. Two of the most famous are the
Great Barrier Reef off the coast in Australia and the Meso-American
Barrier Reef off the coast of Belize.
3. Coral atolls – coral atolls are rings of coral that grow on top of
sunken volcanoes in the ocean. They begin as fringe reefs
surrounding a volcanic island; then, as the volcano sinks, the reef
continues to grow until, eventually, only the reef remains. Atolls are
usually circular or oval, with a central lagoon. Parts of the reef
platform may emerge as one or more islands, and breaks in the reef
provide access to the central lagoon.
22
5.3 CORAL REEFS
CORAL REEF DISTRIBUTION
Coral reefs are mostly found in the tropics in warm (21°C-30°C
(70°F-85°F), shallow water. They are found off the east coast of
Africa, the south coast of India, in the Red Sea, and off the coasts of
northeast and northwest Australia. There are also coral reefs off the
coast of Florida and in the Caribbean. The Great Barrier Reef (NE
Australia) is the largest coral reef in the world and is over 2,000 km
(1,257 miles) in length. The Mesoamerican Barrier Reef is the
second longest barrier reef in the world and extends from the
southern half of the Yucatan Peninsula in Mexico through Belize to
Honduras.
REFERENCES & FURTHER READING
http://www.coris.noaa.gov/about/what_are/
http://www.enchantedlearning.com/biomes/coralreef/coralreef.shtml
23
5.3 CORAL REEFS
5.3.2 Coral Reef Life
24
5.3 CORAL REEFS
HARD CORALS
Corals can be considered as either hard or soft depending on their
consistency and the nature of their skeletons. Hard corals are reefbuilding corals that secrete a hard external limestone skeleton. This
skeleton remains when the corals die and forms a base upon which
other corals can grow. Hard corals grow in three basic forms,
namely, massive, branching, and plate. Examples include brain coral
(a massive coral), elkhorn and staghorn corals (branching corals),
and leaf coral (a plate coral). In the Cayman Islands, about 44
species of hard coral can be found.
SOFT CORALS
Soft coral polyps form a skeleton by secreting a flexible horn-like
substance (gorgonin) into which calcium carbonate (limestone) is
embedded. This arrangement results in the formation of pliable
bushy or fan-shaped colonies. Soft corals also extend their polyps
during the day to capture prey which adds to the illusion of their
being fuzzy bushes or intricately-branched trees and some of the
most common are the sea fans, sea fingers and sea whips.
25
5.3 CORAL REEFS
SPONGES
Sponges are conglomerations of simple cells and are some of the
most primitive invertebrate animals surviving today. They are
composed of an internal skeleton of needle-sharp spicules that are
interwoven with strands of protein (spongin) to give the sponge its
tough and rubbery texture. Many varieties of sponge can be found
in Florida and the Caribbean including the commonly seen basket,
vase and tube sponges. Sponges feed on phytoplankton and
zooplankton by drawing in water through pores in their skin. The
water is then propelled by flagella through a series of canals and
chambers, from which food is filtered, before it is expelled from large
vents, called oscula.
SEA STAR
Sea stars (or starfish) are soft-bodied marine animals with five arms.
Sea stars are echinoderms, a large group of invertebrates which
include sea urchins, sand dollars, sea cucumbers and brittle stars.
Sea stars typically live in the middle of a tidal range and can survive
short periods of exposure to air as the tide retreats.
26
5.3 CORAL REEFS
SEA URCHIN
Sea urchins are echinoderms.
They are round, spiny and
herbivorous invertebrates that graze on algae and detritus from
grass beds and rocky areas. Many sea urchins have long, sharp
spines on their backs, which protect them from predators such as
fish, crabs, moray eels and sea otters. However, their underside is
often spineless and they are vulnerable to attack from that side if the
predator can turn the sea urchin over.
HERMIT CRAB
Hermit crabs are decapod crustaceans. Most hermit crabs have
long soft abdomens which they protect by living inside the empty
seashells of sea snails (marine gastropod molluscs). The tip of the
hermit crab's abdomen is adapted to clasp strongly onto the snail
shell. There are about 500 species of hermit crabs in the world
mainly living on shallow coral reefs and shorelines or deep sea
bottoms. In the tropics, however, some species are terrestrial and
can be large, such as the soldier crab (Coenobita clypeatus) and
coconut crab (Birgus latro). The coconut crab is the world’s largest
arthropod weighing up to 4 kg (9 lbs) and with a leg span of 2 m (6
ft).
27
5.3 CORAL REEFS
28
FISHES
A wide variety of reef fishes can be found on Caribbean reefs.
Some common fish families include:
Bony Fish Families:
Angelfish
Butterflyfish
Damselfish – Sergeant Majors
Goatfish
Grunts
Jacks
Moray eels
Parrotfish
Sea basses
Snappers
Surgeonfish
Tarpon
Triggerfish
Wrasses
Cartilaginous Fish Families:
Eagle rays
Stingrays
Nurse sharks
Requiem sharks – bull shark, sandbar shark, whitetip reef shark
Interesting!
Parrotfish bite out chunks of the
rock-hard coral to dredge out the
algae around and within it for food.
In order to rasp the encrusting
algae from the corals, Parrotfish
use a set of teeth that are fused
into solid plates and are ideal for
biting the rock-hard coral skeletons.
The parrotfish's ingestion and
excretion of the undigested coral
skeletons is thought to be the main
source of the white sand so often
seen and admired on tropical
beaches.
5.4 OCEAN LIFE
5.4 OCEAN LIFE
29
5.4 OCEAN LIFE
5.4 OCEAN LIFE
5.4.1 Cnidarians
If you’ve ever been stung by anything in the ocean, the chances are
that it was probably by one of the cnidarians. It might have been a
moon jellyfish in which case the sting was probably scarcely
noticeable. Alternatively, you might have brushed up against a fire
coral in which case the sting was mildly painful. However, if it was a
Portuguese man-of-war, the sting would have been excruciatingly
painful.
The word “cnidarian” is pronounced “ne-dare-ee-an” or “nigh-dareee-an” (the “c” is silent) and comes from the Greek word “cnidos”
which means “nettle”.
This is somewhat appropriate as all
cnidarians have stinging cells. The cnidarians count some of the
oldest, largest and most poisonous creatures on Earth among them.
Some of their features are as follows:
30
Interesting!
Many scientists are trying to get
away from using the term “jellyfish”
and using the term “jellies” instead
because jellyfish are not “fish” but
invertebrates and members of the
cnidarian phylum.
Interesting!
A group of fish is called a “school”.
A group of jellyfish is known as a
“smack”.
5.4 OCEAN LIFE
 Ancient simple animals
 Fossil records date back to the Precambrian era (about 550 million
years ago)
Very diverse; about 10,000 species
 Extremely varied and range in size from a few millimeters to over
30 meters in length
 With few exceptions, the cnidarians are marine animals
 All are predators and carnivorous; major part of their diet consists
of crustaceans and fish
 Cnidarians spend their lives in sessile polyp form, free-swimming
medusa form, or a mix
 In polyp form, tentacles oriented upwards; in medusa form,
tentacles oriented downwards
 Both asexual (polyp form) and sexual (medusa form) reproduction
occurs
 No specialized excretory or respiratory organs but do have gonads
& simple nervous system
There are four major classes of cnidarians:
1. Anthozoa – Sea anemones, Corals
2. Hydrozoa – Siphonophores, Hydroids
3. Scyphozoa – True Jellyfish
4. Cubozoa – Box Jellyfish
31
5.4 OCEAN LIFE
32
CNIDARIAN CLASSIFICATION
5.4 OCEAN LIFE
33
CNIDARIAN FEATURES
BODY
A cnidarian’s body consists of a sac with a digestive cavity and a single opening that functions as mouth and anus.
Tentacles surrounding the mouth contain stinging cells for offense and defense. A cnidarian has radial symmetry
(i.e. whichever way it is cut along its central axis, the resulting halves are mirror images of one other). A cnidarian is
composed of two layers of tissue, called the ectoderm and endoderm (or gastroderm), which are held together by a
gelatinous mesoglea containing only scattered cells.
STINGING CELLS (“NEMATOCYSTS”)
Cnidarians have specialized cells that carry stinging organelles called nematocysts. These specialized stinging
structures are a characteristic of the phylum and are borne in the tentacles and other body parts. Cnidarians employ
these stinging cells to kill prey. The nematocysts function by a chemical or physical trigger that causes it to eject a
coiled fiber with a barbed and poisoned hook that can stick into prey. Dead or paralyzed prey is pushed into the
cnidarian's oral opening by the tentacles and digested in the gastrovascular cavity. All undigested food, waste &
other secretions leave through the same oral opening.
BODY FORMS & LIFESTYLES
The cnidarians have two characteristic body forms and lifestyles. The sessile polyp form is more or less cylindrical,
attached to its substratum at its aboral (opposite the mouth) end, with the mouth and surrounding tentacles at the
upper (free) end. The motile medusoid form is flattened, with the tentacles usually located at the body margin.
Generally, the cnidarians have life-cycles that alternate between asexual polyps and sexual free-swimming medusae
although there is considerable variation within this pattern. For example, the Anthozoan medusal stage is virtually
non-existent – once the larva fuses with the substratum and develops into the polyp, it grows sessile and no longer
metamorphosizes into the medusal stage.
Among the Scyphozoans and Cubozoans, the medusae are the
dominant form in the life-cycle, and the polyps are in turn reduced or absent.
5.4 OCEAN LIFE
ANTHOZOA – SEA ANEMONES, CORALS
1. Sea Anemones
Sea anemones are simple animals (cnidarians) that are often
attached to the sea bottom. Sea anemones have cylindrical bodies
that are surrounded by upward-facing tentacles. The tentacles have
stinging cells on them which kill prey and move the food into a sea
anemone’s mouth. The mouth leads into the body cavity which
digests the food. A continuous current of water through the mouth
circulates through the body cavity and removes waste.
Sea
anemones are found in cold and warm waters. Many are colourful,
and large species can be 1 m (3 ft) in diameter.
2. Corals
Corals are often misperceived as rock or vegetation but they are
actually colonies of simple animals. A ring of tentacles is found at
the upper end of each coral polyp. The tentacles contain poisonous
stinging cells (nematocysts) that are used to kill zooplankton or fish.
As the prey drops, it is funnelled by the tentacles into the mouth and
digested in the digestive cavity. The food obtained by one polyp can
also be passed to other polyps in the colony and a coral, therefore,
does not have a single mouth but hundreds or thousands, each of
which serves to feed the animal as a whole.
34
5.4 OCEAN LIFE
Coral polyps also contain symbiotic algae called zooxanthellae
within their digestive cavity. The polyps benefit from the oxygen
produced in the algal photosynthesis reaction and from the removal
of carbon dioxide waste produced by polyp respiration. The
zooxanthellae benefit from the ammonia waste excreted by the
polyps as it can be broken down and used by the algae to build
proteins. In addition, the polyps provide the algae with carbon
dioxide from their respiration, necessary for algal photosynthesis.
Corals have two main consistencies – hard/stony or soft.
Hard Corals
A hard coral polyp secretes a calcium carbonate (limestone) cup
around itself, which is fused with others to form boulder or rock-like
structures. This process is slow but the efforts of one generation are
not lost for subsequent generations can build over the skeletal cups
of their ancestors allowing the coral to spread over a reef. An
example of a hard coral is brain coral.
Soft Corals
In contrast, soft coral polyps secrete a horn-like substance
(gorgonin) into which calcium carbonate is embedded. This
arrangement gives the soft corals greater flexibility than their hard
coral counterparts, allowing them to form more pliable bushy or fanshaped colonies. An example of a soft coral is the purple sea fan.
35
5.4 OCEAN LIFE
Corals Reefs Worldwide:
Great Barrier Reef
Belize
Red Sea
Caribbean, etc.
36
5.4 OCEAN LIFE
Problems:
1. Climate Change
A sobering study by the World Conservation Union released in
October 2005 determined that nearly half of the world's coral reefs
may be lost in the next 40 years unless urgent measures are taken
to protect them against the threat of climate change.
“Coral Bleaching” – algae give corals their multi-colours; when water
is too warm, the algae are ejected. Without the symbiotic algae,
coral skeletal growth and repair rates are slower and the coral may
die.
2. Pollution
Corals cannot clean themselves of some forms of pollution. Other
forms of pollution cause corals to secrete too much mucus which
leads to infection.
3. Physical Damage
Natural forces (e.g. storms)
Humans (e.g. boat anchors, swimmers, divers)
4. Slow Growth Rates
Many corals grow slowly (perhaps only 1 cm (0.5 in) per year) and it
can take many years to repair damage.
37
5.4 OCEAN LIFE
HYDROZOA – SIPHONOPHORES, HYDROIDS
A siphonophore resembles a jellyfish but it is not actually an
individual organism. Siphonophores, such as the Portuguese Manof-War, are really colonies of specialized individuals so that, in
extreme cases, individuals essentially function as organs of the
whole. For example, one individual in the group transforms itself
into a gas-filled float while others form stinging tentacles that kill
prey.
A Portuguese Man-of-War's tentacles hang well below the float and
can be up to 9 m (30 ft) long. Stinging cells at the tips are used to
kill prey, such as crustaceans, fish, and plankton. The prey is then
lifted into the colony's float, where other members do the work of
digestion. Nutrients are shared through a connected gut system and
a network of nerves helps the individuals communicate.
A
Portuguese Man-of-War's sting is extremely painful to humans and
wounds may not heal for weeks.
Similarly, hydroid colonies are also comprised of several different
types of individuals: some function in feeding, some in defence, and
others in reproduction.
Other hydrozoans form massive colonies that resemble true corals.
For example, the so-called “fire corals” are not really corals at all but
hydrozoans.
Hydrozoans alternate between sessile polyp & free-swimming
medusa stage.
38
39
5.4 OCEAN LIFE
SCYPHOZOA – TRUE JELLYFISH
 No head, skeleton or special organs for respiration and excretion
 Stings vary in potency – mild to highly potent
 Huge range in size from 12mm to 2m across the bell
 The collective noun for a group of jellyfish is a “smack”
 Alternate between sessile polyp & free-swimming medusa phase;
medusa phase dominates
Moon jellyfish (Aurelia sp.)
To 300mm (12 in) across bell
Stings mild to humans
Red-striped sea nettle (Chrysaora fuscescens)
To 1 m (3 ft) diameter, tentacles 5 m (15 ft)
Found from Alaska (AK) to California (CA)
Lion’s mane jellyfish (Cyanea arctica)
To 2m diameter; tentacles >40m (130 ft)
Stings very painful to humans
Interesting!
The lion’s mane jellyfish is one of
the world’s longest animals with
tentacles reaching more than 40 m
(130 ft).
5.4 OCEAN LIFE
CUBOZOA – BOX JELLYFISH
Look like basic jellyfish but are square or box shaped
 Tentacles are evenly spaced on each corner of the bell
 Have well-developed eyes and can see fairly well
 May also have a rudimentary brain
 Most jellyfish drift but box jellyfish can swim quite quickly
 Sometimes called sea wasps
 About 20 species found in tropical and sub-tropical waters
Cubozoans can be divided into two groups:
1. Chirodropids
Stinging cells usually only on tentacles
Usually larger: Chironex fleckeri 300-385 mm (12-15 in) across bell
Multiple tentacles per corner of bell. For example, Chironex fleckeri
(large box jelly) has up to 60 tentacles (15 per corner of the bell)
2. Carybdeids
Stinging cells on both body & tentacles
Usually smaller: Carukia barnesi 10 mm (0.4 in) across bell
Usually one tentacle per corner of bell. For example, Carukia
barnesi has 4 retractile tentacles (1 per corner of the bell) each up to
750 mm (30 in) long.
40
5.4 OCEAN LIFE
Some box jellyfish are intensely poisonous and can cause human
fatalities. The bell of the Australian Irukandji jelly, Carukia barnesi,
for example, is only about the size of a human fingernail (1 cm) and
its tentacles are like long thin threads. The sting may be extremely
painful for several weeks and can sometimes kill humans.
REFERENCES & FURTHER READING
http://www.earthlife.net/inverts/cnidaria.html – The Phylum Cnidaria
http://www.ucmp.berkeley.edu/cnidaria/cnidaria.html – Introduction to Cnidaria
http://www.ucmp.berkeley.edu/cnidaria/Chironex.html - Chironex
http://www.tolweb.org/tree?group=Cnidaria – Cnidaria
http://www.reef.crc.org.au/publications/brochures/Stingingjellyfishfront.htm – Jellyfish in Australia
http://www.iucn.org – World Conservation Union
41
5.4 OCEAN LIFE
5.4.2 Reef Fish
There are about 350 different marine fish species in the Caribbean.
To differentiate between them, it is often helpful to initially classify
them according to their various characteristics.
All fishes are classed as either jawless or jawed vertebrates:
1. JAWLESS FISHES
Jawless fishes, such as lampreys & hagfishes, are primitive fishes
with no jaws, scales, pelvic or pectoral fins. Lampreys are both
parasitic and non-parasitic. Parasitic lampreys cling to their prey by
suction with their oral disk. They rasp a hole in their prey and suck
out its blood and body fluids. Non-parasitic lampreys do not feed as
adults. Most lampreys live in freshwater; those that enter the sea
return to rivers to spawn. Hagfishes scavenge on dead or dying
fishes by rasping their way into the fish and eating the flesh.
Hagfishes produce great quantities of slime and have vestigial eyes
that are covered by skin. Hagfishes are marine and usually found in
deep cold water.
42
Interesting!
The plural of fish can be fish or
fishes. The distinction depends
on the number and species of
fish. If you have more than one
fish but they are the same species
then the plural is “fish”. For
example, if I have three flounders,
I have three fish. If there is more
than one species then the plural is
“fishes”. Thus, if I have two
flounders and one skate, I have
three fishes.
5.4 OCEAN LIFE
2. JAWED FISHES
Jawed fishes are further divided into bony or cartilaginous fishes.
(A) BONY FISHES
Bony fishes have skeletons made of bone. Bony fish are subdivided into many different orders and families such as angelfish,
butterflyfish, damselfish, goatfish, grunts, jacks, moray eels,
parrotfish, sea basses, snappers, surgeonfish, tarpons, triggerfish, &
wrasses. Bony fish have cycloid (round), ctenoid (comb-like) or
ganoid (diamond-shaped) scales, and a pair of gill covers, and most
bony fish also have swim bladders to control their buoyancy.
(B) CARTILAGINOUS FISHES
Cartilaginous fishes have skeletons primarily made of cartilage and
most have sharp, placoid (plate shaped) scales covering their skins.
Cartilaginous fishes have no gill covers or swim bladders and use
large, oil-filled livers to help keep them buoyant. The best known
cartilaginous fishes are the sharks & rays. Sharks and rays are
further divided into multiple orders and families such as the requiem,
sand tiger and nurse shark families and the skate, sawfish, eagle
ray, and devil ray families. There are about 30 families and 355
species of sharks, and 11 families and 470 species of rays.
43
5.4 OCEAN LIFE
44
5.4 OCEAN LIFE
ANGELFISH
Angelfish bodies are deep and about the size of a dinner plate
They are diurnal
Eat sponges; unusual as many animals cannot eat sponges
Usually found singly or in pairs
E.g. French angelfish (Length to 30 cm or 12 in)
Black with yellow-edged scales
Young French angelfish will act as cleaners for other fish
Juvenile French angelfish are striped
Become mottled as they mature
45
5.4 OCEAN LIFE
BUTTERFLYFISH
Butterflyfish bodies are deep and flattened with bright colours and
patterns on them
Long, pointed mouths for plucking out coral polyps as food
Feed mainly on hard and soft corals (gorgonians), polychaete
worms, and tunicates
Typically seen singly or in pairs and are active during the day
E.g. Foureye butterflyfish (Length to 8 cm or 3 in)
White body with large “spot” below rear of dorsal fin – spot is on
body
Dark, diagonal lines that meet at the mid-side of the body
DAMSELFISH
Territorial and guard patches of coral
Have little fear – will even come at divers if they get too close
Lay adhesive eggs in clusters on hard surfaces; nest guarded by
male
Produce chirping sounds; used in courtship, territorial defence &
species recognition
E.g. Sergeant major (Length to 18 cm or 7 in)
Bright yellow above, silvery grey below with 5 stripes
Eats algae and various invertebrate larvae
Adults form large feeding groups of up to several hundred fish
46
5.4 OCEAN LIFE
EAGLE RAYS
Large, free-swimming rays; “fly” through the water by flapping their
long pectoral fins
Gather in schools of hundreds or thousands
Feed on bottom organisms such as molluscs and clams
Have flattened teeth which are suited to crushing shellfish
Have a strong, serrated, venomous spine near base of tail (like
stingrays)
Individuals occasionally seen with chunks missing from a “wing” due
to shark bites
E.g. Cownose ray (To 1 m or 3 ft across disk)
Dark brown to olive above with no spots or marks
Snout squarish with an indentation in the centre
Bears live young (like all eagle rays)
GOATFISH
Bottom-dwelling fishes that have long, fleshy “barbels” (“whiskers”)
under their chin
Swim along the sandy bottom stirring sand with their barbels to
locate food
E.g. Yellow goatfish (Length to 38 cm or 15 in)
Yellow stripe from eye to yellow caudal fin
Feeds on bottom-dwelling invertebrates
Often found in schools
Forms schools with smallmouth grunts possibly for protection
47
5.4 OCEAN LIFE
GRUNTS
Tend to feed at night and congregate by day in large schools on
reefs
Grind their teeth; this makes a grunting noise hence their name
E.g. Porkfish (Length to 38 cm or 15 in)
Two black bars on head and front part of body
Body with alternating blue and yellow stripes; fins yellow
Young remove parasites from other fish
JACKS
Large, strong, fast-swimming fishes
Predatory; feed on a wide variety of invertebrates and fishes
Lack bright colours; silvery on sides and darker above
Important food and game fish
E.g. Lookdown (Length to 30 cm or 12 in)
Body is extremely compressed and deep
Front of head very steep
48
5.4 OCEAN LIFE
MORAY EELS
Morays are predators that feed on fishes, octopuses, crustaceans and
molluscs
No pectoral fins; dorsal, caudal & anal fins continuous hence “snake-like”
appearance
Gill opening reduced to a single circular opening
Habit of gaping is not usually a threat but for respiration
Have long, sharp teeth and powerful jaws that can crush bone
E.g. Blackedge moray (Length to 53 cm or 21 in)
Dark brown with pale spots; dorsal fin black edged (hence name)
E.g. Green moray (Length to 2.4 m or 96 in)
Green coloration is caused by a yellowish mucus blending with its dark
blue body colour
NURSE SHARK Nurse Shark Family
Rusty brown with small yellowish eyes
No nictitating membrane on eye
Mouth small; teeth in a crushing series
Feeds on crustaceans and shellfish
Use their thick lips to create suction and pull prey from holes & crevices
Has “barbels” (“whiskers”) front edge of each nostril
Barbels used to find food on the ocean bottom.
Caudal fin with no distinct lower lobe
Will bite if provoked but otherwise relatively harmless
Large eggs in horny capsules
Length to 4.3 m (14 ft) but usually less than 3 m (10 ft)
49
5.4 OCEAN LIFE
PARROTFISH
Parrot-like beak from fused teeth
Eat corals and algae
Swim using their pectoral fins
E.g. Blue parrotfish (Length to 122 cm (4 ft); usually 61 cm (2ft))
Sky to royal blue body
Blunt snout
Teeth white
SANDBAR SHARK
Requiem Shark Family
Heavy body
Dark grey to brown above; becoming paler below
Infamous relatives are the Bull, Tiger and Oceanic Whitetip sharks
Bears live young (like all requiem sharks)
Length to 3 m (10 ft)
50
5.4 OCEAN LIFE
SEA BASSES
The sea bass family consists of sea basses and groupers. Sea bass
family:
Small to very large fishes with 7-11 spines on dorsal fin
Mainly tropical fishes but are also found in temperate shores
Important food fish for humans
Usually solitary and territorial; non-schooling fishes
E.g. Chalk bass (Length to 6.4 cm or 2.5 in)
Orange-brown above with pale blue bands; top of head un-scaled
Have 10 spines in dorsal fin
Synchronously hermaphroditic
Common near coral reefs
SNAPPERS
Predatory fish
Snappers from deeper, rocky slopes are usually red; reef types are
tan and yellow
Important food and game fish
E.g. Yellowtail snapper (Length to 76 cm or 30 in; 2.3 kg / 5 lbs)
Bright yellow stripe from snout tip to caudal fin
Quite common on a reef and will often follow divers around
E.g. Vermillion snapper (Length to 76 cm or 30 in)
Head, body, and fins entirely pale red becoming silvery below;
protruding lower jaw
51
5.4 OCEAN LIFE
STINGRAYS
Most stingrays eat clams, mussels, and oysters
Have flattened teeth which are suited to crushing shellfish
Have a thin, whip-like tail with one or more barbed spines near the
base of the tail
E.g. Southern stingray (To 53 cm or 21 in across disk)
Disk almost perfect rhombus
Most stingrays are bottom-dwellers; often lie submerged in sand
except for the eyes
Whip-like tail with venomous spine; note: spine venomous, not the
tail itself
Bears live young (like all stingrays)
SURGEONFISH
Named for the spine on each side of the caudal peduncle. This
spine folds forward against the body like the blade of a pocket-knife.
Spine can inflict painful wounds if fish is grasped around the caudal
peduncle.
E.g. Blue tang (Length to 23 cm or 9 in)
Uniformly bright blue body usually with narrow dark lengthwise lines
Narrow yellow line where spine folds against caudal peduncle
52
5.4 OCEAN LIFE
TARPONS
Large, powerful, predatory fish
Important game fish
E.g. Tarpon (Length to 2.4 m or 96 in and 136 kg or 300 lb)
Silvery
Large mouth; protruding lower jaw
Very large scales
TRIGGERFISH
3 dorsal spines with locking device; the first one long and strong; the
other two spines small
Scales regular, plate-like, forming coarse armour over body
Most triggerfish produce grunting sounds
Mouth small but jaws strong and teeth well-developed
Triggerfish eat crustaceans (crabs, lobsters), octopuses, sea urchins
and corals
Will bite off crustacean limbs and sea urchin spines using their teeth
and jaws like bolt-cutters
E.g. Queen Triggerfish (Length to 61 cm or 24 in)
Bluish; orange chin and chest; bright blue and gold marks
53
5.4 OCEAN LIFE
54
WRASSES
Varied in size from very small to huge
Swim by flapping pectoral fins
Most are non-schooling
Most have protruding teeth
E.g. Hogfish (Length to 90 cm or 36 in)
Body deep; reddish; dark mask; 3 long dorsal spines
REFERENCES & FURTHER READING
http://www.fishbase.org
Robins, C.R. et al., A Field Guide to Atlantic Coast Fishes of North America, Houghton Mifflin Pub.
(1986)
5.4 OCEAN LIFE
55
5.4.3 Sea Turtles
Sea turtles are reptiles that are part of the turtle and tortoise order.
A sea turtle’s body is partially covered by a shell. This shell consists
of two parts; an upper carapace and a lower plastron. Unlike other
turtles, a sea turtle’s head & flippers cannot be pulled inside of its
shell. There are 7 species:
 Green
 Loggerhead
 Hawksbill
 Flatback
 Kemp’s Ridley
 Olive Ridley
 Leatherback
All species have shells with horny scales (“scutes”) except the leatherback which is covered with leathery
skin. The leatherback is one of only a few reptiles capable of regulating its internal body temperature.
56
5.4 OCEAN LIFE
HOW LARGE ARE SEA TURTLES? HOW LONG DO THEY LIVE?
The largest sea turtle is the leatherback, which has a carapace length of about 1.6 m (64 in) and can
weigh 590 kg (1300 lbs). Sea turtles can possibly live over 100 years depending on species. The
following outlines the weight and average carapace length of the sea turtles:
Species
Green
Weight
Length
136-227 kg
300-500 lbs
99 cm
39 in
91-159 kg
200-350 lbs
84-102 cm
33-40 in
40-73 kg
89-160 lbs
76-91 cm
30-36 in
71 kg
156 lbs
76-97 cm
30-38 in
35-45 kg
78-100 lbs
61-71 cm
24-28 in
Olive Ridley
< 45 kg
< 100 lbs
56-76 cm
22-30 in
Leatherback
363-590 kg
800-1300 lbs
162 cm
64 in
Loggerhead
Hawksbill
Flatback
Kemp’s Ridley
57
5.4 OCEAN LIFE
WHERE ARE SEA TURTLES FOUND?
Sea turtles are found in many of the world’s oceans.
Green
Temperate and tropical waters
Atlantic (Central America, Bahamas, U.S.) Pacific (Baja, CA to Peru)
Loggerhead
Temperate and subtropical waters
Newfoundland to Argentina
Hawksbill
Tropical
Atlantic, Pacific, Indian Oceans
Flatback
Tropical
Australia northern coastal waters only
Kemp’s ridley
Temperate and tropical waters
Gulf of Mexico. Juveniles along eastern seaboard of the USA to Cape Cod
Olive ridley
Tropical waters
Mainly in Pacific and Indian Oceans, a few in Atlantic
Leatherback
Arctic to tropical waters
Canada, Iceland, Norway, NZ, Chile
5.4 OCEAN LIFE
WHAT DO SEA TURTLES EAT?
Sea turtles feed on a variety of items including turtle grass, jellyfish,
sponges, fish and crustaceans.
HOW DO SEA TURTLES REPRODUCE?
A female sea turtle come ashore to lay her eggs. The female digs a
burrow with her hind legs, lays a batch of eggs and covers them with
sand. The temperature of the sand on the beach determines the sex
of the hatchling – warmer temperatures result in female hatchlings;
cooler temperatures result in male hatchlings. Hatchlings dig their
way out of the burrow and head for the sea.
WHY DO MOST TURTLES NEVER MAKE IT TO ADULTHOOD?
Hatchlings and young turtles are preyed upon by many predators
(e.g. raccoons, crabs, foxes, sea birds and large fish). Sea turtles
are hunted by humans for meat, eggs, skin and shells to produce
face cream, cosmetics and souvenirs. Habitat destruction has also
drastically reduced the number of available beaches for breeding.
As a result, only 1% of sea turtle eggs will make it to adulthood.
58
5.4 OCEAN LIFE
59
WHAT IS THE “ARRIBADA”?
All sea turtles have solitary nesting except the Ridleys which arrive
and nest as a mass. This is called the “arribada” or the “arrival” in
Spanish.
WHY ARE GREEN TURTLES BROWN?
The green turtle is named for its green body fat (“calipee”) not its
carapace colour. Calipee is used in making turtle soup.
WHAT IS THE STATUS OF SEA TURTLES?
All sea turtles are either endangered or threatened. Sea turtles are
protected in the USA under the Endangered Species Act and around
the world by CITES (Convention on the International Trade of
Endangered Species of Flora and Fauna).
REFERENCES & FURTHER READING
http://www.cccturtle.org
http://www.seaworld.org/animal-info/info-books/sea-turtle/topic-list.htm
Waller, Geoffrey, Burchett, Michael and Dando, Marc, Sea Life, A Complete Guide to the Marine
Environment, Smithsonian Institution Press, Washington 1996. ISBN: 1-56098-633-6
5.5 ACTIVITIES
5.5 ACTIVITIES
60
5.5 ACTIVITIES
61
5.5 ACTIVITIES
5.5.1 Animal, Vegetable or Mineral
CORE ACTIVITY
(a) Place the following into one of the three categories. If it is not an animal or a “vegetable” (i.e. plants
or algae) then treat it as a mineral.
• Mudskipper
• Red mangrove
• Brain coral
• Elkhorn coral
• Sea urchin
• Sea anemone
• Coral skeleton
• Sponge
• Zooxanthella
• Phytoplankton
• Sea cucumber
• Sea star
• Kelp
• Sea grass
62
5.5 ACTIVITIES
Animal
Vegetable
Mineral
5.5 ACTIVITIES
63
ANSWERS
(a) Place the following into one of the three categories. If it is not an animal or a “vegetable” (i.e. plants
or algae) then treat it as a mineral.
• Mudskipper
• Red mangrove
• Brain coral
• Elkhorn coral
• Sea urchin
• Sea anemone
• Coral skeleton
• Sponge
• Zooxanthella
• Phytoplankton
• Sea cucumber
• Sea star
• Kelp
• Sea grass
64
5.5 ACTIVITIES
Animal
Vegetable
Mineral
Mudskipper
Brain coral
Elkhorn coral
Sea urchin
Sea anemone
Sponge
Sea cucumber
Sea star
Red mangrove
Zooxanthella
Phytoplankton
Kelp
Sea grass
Coral skeleton
5.5 ACTIVITIES
65
5.5.2 Coral Reef Log
EXTENDED ACTIVITY
If it is practicable and safe to do so, organize an excursion where pupils can swim or snorkel near a reef.
Have each student keep a log of all animals and plants seen while swimming or snorkelling. Use a page
for each organism. Look up the organism using a field guide or use the Web, place it into its appropriate
group (animal/plant, vertebrate/invertebrate, etc.) and keep short notes about each organism’s features.
Include a drawing or photo of the organism.
5.5 ACTIVITIES
SAMPLE TABLE OF CONTENTS
Animals
Vertebrates
• Fishes
• Birds
• Reptiles (iguanas, alligators, snakes)
• Amphibians
• Mammals
Invertebrates
• Molluscs (clams)
• Echinoderms (sea stars, sea urchins)
• Crustaceans (shrimps, crabs, lobsters)
• Cnidarians (sea anemones)
Plants
Grasses
•…
•…
•…
Flowering Plants
•…
•…
•…
66
5.5 ACTIVITIES
5.5.3 Coral Identification
CORE ACTIVITY
(a) Identify the following corals and sponges by
drawing an arrow between the label and animal:
(b) Which of the illustrated corals are hard
corals?
(c) Which of the illustrated corals are soft corals?
67
5.5 ACTIVITIES
ANSWERS
(a) Identify the following corals and sponges by
drawing an arrow between the label and animal:
(b) Which of the illustrated corals are hard
corals?
Brain Coral, Elkhorn Coral and Staghorn Coral
(c) Which of the illustrated corals are soft corals?
Sea Fan
68
5.5 ACTIVITIES
5.5.4 Reef Fish Identification
CORE ACTIVITY
(a) What are some of the differences between bony and cartilaginous fishes?
(b) Write the name of the following fishes under its picture.
• French angelfish
• Sandbar shark
• Blackedge moral eel
• Southern stingray
• Foureye butterflyfish
• Blue parrotfish
• Nurse shark
• Tarpon
• Queen triggerfish
69
5.5 ACTIVITIES
(c) Which of the illustrated fishes are bony fishes?
(d) Which of the illustrated fishes are cartilaginous fishes?
70
5.5 ACTIVITIES
ANSWERS
(a) What are some of the differences between bony and cartilaginous fishes?
Bony fishes
• Skeletons made of bone
• Cycloid (round), ctenoid (comb-like) or ganoid (diamond-shaped) scales
• A pair of gill covers
• Most bony fish also have swim bladders to control their buoyancy
Cartilaginous fishes
• Skeletons primarily made of cartilage
• Most have sharp, placoid (plate shaped) scales covering their skins
• Cartilaginous fishes have no gill covers
• No or swim bladders and use large, oil-filled livers to help keep them buoyant
(b) Write the name of the following fishes under its picture.
• French angelfish
• Sandbar shark
• Blackedge moral eel
• Southern stingray
• Foureye butterflyfish
• Blue parrotfish
• Nurse shark
• Tarpon
• Queen triggerfish
71
5.5 ACTIVITIES
72
(c) Which of the illustrated fishes are bony fishes?
French angelfish, foureye butterflyfish, blackedge moray eel, blue parrotfish, queen triggerfish, and
tarpon
(d) Which of the illustrated fishes are cartilaginous fishes?
Nurse shark, sandbar shark, southern stingray
5.5 ACTIVITIES
5.5.5 Sea Turtles
CORE ACTIVITY
(a) Colour in the green turtle dark brown or olive and add the following labels to the picture:
• Eye
• Nuchal – large scute at the front of the turtles carapace by the neck
• Claw
• Tail
• Flipper
• Central scute
• Costal (side) scute
• Marginal (edge) scute
• Nostril
73
5.5 ACTIVITIES
74
5.5 ACTIVITIES
(b) Write a brief description of sea turtles
(c) Which is the largest sea turtle? How long do sea turtles live?
(d) What do sea turtles eat?
(e) How do sea turtles reproduce?
(f) Why do most turtles never make it to adulthood?
(g) What is the “arribada”?
(h) Why are Green turtles brown?
(i) Where are sea turtles found?
(j) What is the status of sea turtles?
75
5.5 ACTIVITIES
ANSWERS
(a) Colour in the green turtle dark brown or olive and add the following labels to the picture:
• Eye
• Nuchal – large scute at the front of the turtles carapace by the neck
• Claw
• Tail
• Flipper
• Central scute
• Costal (side) scute
• Marginal (edge) scute
• Nostril
76
5.5 ACTIVITIES
77
5.5 ACTIVITIES
78
(b) Write a brief description of sea turtles
Sea turtles are reptiles that are part of the turtle and tortoise order. A sea turtle’s body is partially
covered by a shell. This shell consists of two parts; an upper carapace and a lower plastron. Unlike
other turtles, a sea turtle’s head & flippers cannot be pulled inside of its shell. There are 7 species of sea
turtle: Green, Loggerhead, Hawksbill, Flatback, Kemp’s Ridley, Olive Ridley & Leatherback. All species
have shells with horny scales (“scutes”) except the Leatherback which is covered with leathery skin.
(c) Which is the largest sea turtle? How long do sea turtles live?
The largest sea turtle is the Leatherback, which grows to about 64” in length and can weigh 1300 lbs.
Sea turtles can possibly live over 100 years depending on species. The following outlines the weight
and average carapace length of the sea turtles:
(d) What do sea turtles eat?
Sea turtles feed on a variety of items including turtle grass, jellyfish, sponges, fish and crustaceans.
(e) How do sea turtles reproduce?
Female sea turtles come ashore to lay her eggs. The female digs a burrow with her hind legs, lays a
batch of eggs and covers them with sand. Sand temperature determines the sex of the hatchling;
warmer -> females; cooler -> males. Hatchlings dig their way out of the burrow and head for the sea.
5.5 ACTIVITIES
79
(f) Why do most turtles never make it to adulthood?
Hatchlings and young turtles are preyed upon by many predators (e.g. raccoons, crabs, foxes, sea birds
and large fish). Sea turtles are hunted by humans for meat, eggs, skin and shells to produce face
cream, cosmetics and souvenirs. Habitat destruction has also drastically reduced the number of
available beaches for breeding. As a result, only 1% of sea turtle eggs will make it to adulthood.
(g) What is the “arribada”?
All sea turtles have solitary nesting except the Ridleys. The Ridleys arrive and nest as a mass. This is
called the “arribada” or the “arrival” in Spanish.
(h) Why are Green turtles brown?
The Green turtle is named for its green body fat (“calipee”) not its carapace color. Calipee is used in
making turtle soup.
(i) Where are sea turtles found?
Sea turtles are found in many of the world’s oceans including the Atlantic, Pacific and Indian oceans.
(j) What is the status of sea turtles?
All sea turtles are either endangered or threatened. Sea turtles are protected in the USA under the
Endangered Species Act and around the world by CITES (Convention on the International Trade of
Endangered Species of Flora and Fauna).