Adaptations to their environment help define animals..
A Tuna consumes as much as 25% of its body weight in food
each day. That’s like a 150 lb person eating 38 lbs of food
each day..
Tunas burn so much energy they tend to “overheat”, so water
temperature is important to them.
Tunas must swim continuously, else they would suffocate
and/or sink to the bottom. They swim from California to
Japan and back, sometimes going 15 – 20 miles per day.
They can go as fast as 68 miles per hour for short times.
A group of animals that share similar “architecture”,
level of complexity, and evolutionary history is called
a phylum. (from “phylon” = tribe!)
Invertebrates – generally soft-bodied
animals lacking a rigid internal skeleton for
the attachment of muscles, but many with a
hard, protective outer covering which can be
continuous ( shell) or segmented ( a lobster
shell).
There are at least 33 invertebrate phyla, and
they range in size from microscopic worms to
giant squids
Phylum Porifera
Over 10,000 species, ranging in size
from a bean to a small automobile!
They are “filter feeders” straining water
through them to obtain suspended
nutrients and plankton. A sponge may
strain 400 gallons of water each day!
Sponges have no digestive systems, nor
do they have a circulatory system,
respiratory system, or nervous system!
Diffusion takes care of it all…
Porifera structure
Phylum Cnidaria (Coelenterata)
Jellyfish, Sea Anemones, and
Corals. These animals use
stinging cells to immobilize their
prey – usually zooplankton and
small fish.They move the victim
to a saclike digestive cavity
where the digested nutrients are
moved by migratory cells to
other parts of the body. There is
only one opening to the digestive
cavity, so indigestible materials
must be eliminated through the
mouth….(yuk)
A “Sea Wasp” is the most
dangerous jellyfish in the
world. It inhabits tropical
waters from Africa to
northeastern Australia, and
can kill a human within 3
minutes! The tentacles of a
large specimen can reach 50
feet long.
Corals are also classified as cnidarians. They are solitary
animals with bodies up to 12 inches in diameter, but most of the
more than 500 species are ant-sized organisms crowded into
colonies. Corals feed at night, and retract into their shells to
escape sunlight and predators.
The structure of Coral
Worms…..
• Are significantly more “advanced” than cnidarians
• Exhibit bilateral symmetry (left and right, not radial)
• Have some concentrations of sensory systems in their “heads”
• Have a “flow through” digestive and excretory system
• Some are parasites, but most are free-living
More information
Click picture for website
An intertidal marine flatworm – the thin body allows
gases, nutrients and waste to diffuse in and out!
Amphitrite, a tubeworm; Eunice, an
active swimming predator;
Serpula, which lives in stony tubes
and grasps prey as it moves by
The Polychaeta are the largest and
most diverse class of marine
annelids. The “feather duster” is a
food/breathing device.
Advanced Invertebrates - Phylum Mollusca
The Mollusks are “softbodied” animals with over
80.000 species. It contains
such diverse members as
clams, snails, octopuses,
and squid. Most mollusks
are marine, and most have
an internal or external
shell. They may share
common ancestry with
annelids.
Mollusca - Gastropods (the snails)
Members of this class usually
inhabit relatively large shells,
where they can seek refuge.
Some gastropods are grazers,
some as suspension feeders,
and some are predators. The
“foot” of a snail will not
“attach” it to ocean
sediments.
Their shells are usually
considered to be beautiful and
complex.
Gill
structure
A nudibranch is a gastropod without a shell. They have a
terrible taste which seems to discourage predators!
Mollusca – the Bivalves (clams, oysters, mussels)
These filter feeders strain large volumes of water through
their gills. They traded mobility for protection
Mollusca – Cephalopods (squids, nautiluses, octopuses)
The most highly evolved mollusks are the
Cephalopods. They have a head
surrounded by a foot divided into
tentacles. They move by creeping across
the bottom, by swimming with special
fins, or by squirting jets of water.
250 pounds!
Phylum Arthropedia – lobsters, shrimp, crabs, krill, and
barnacles
These animals have been very successful, in spite of the fact
they have not developed the complex nervous systems of
cephalopods, nor do they have great intelligence or great
eyesight (like squids!). Their bodies are a variation of
annelids – bilaterally symmetric with a pair of appendages per
segment.
What they do have are:
• An exoskeleton – strong, lightweight, form-fitted (chitin)
• Striated muscle – quick, strong lightweight
• Articulation – they can bend their appendages
Generalized arthropod and vertebrate growth curves – the
exoskeleton must be shed each time for the arthropod to grow.
This is a time of particular vulnerability for the organism.
Largest class of arthropods – the insecta – is poorly represented
in the sea. (5 species of “water striders”)
The class crustacea has over 30,000 primarily marine species.
Their bodies usually have between 16 – 20 segments, with
specialized appendages. About 70% of all zooplankton are
crustaceans.
Crustaceans dominate the world of marine animals!
A molting crab!
Phylum Echinodermata
The exclusively marine phylum Echinodermata has about
6,000 species. They lack eyes or brains, but have developed a
number of adaptations which have made them successful.
They have a body based on 5-sided symmetry.
The 5-sided jaw of a sea urchin
Web site for more info!
Five classes of Echinoderms. Four most common are:
• Asteroidea – the sea stars
• Ophiuroidea – the brittle stars
• Echinoidea – the sea urchins and sand dollars
• Holothuroidea – the sea cucumbers
Starfish have a water-vascular
system which can be used to
open the shells of a clam or
mussel.
Ophiuroids have long, slender arms which they can
“break off” (and eventually regenerate) if this will
help them escape. They are perhaps the most widely
distributed benthic (bottom-dwelling) marine
animals
Echinoids are very familiar to most coastal residents.
Sand Dollars
and
Sea Urchins
are examples.
Holothuroids are the well-named “sea cucumbers” .
Most of them feed by thrusting small, sticky appendages
into the surrounding sediments, retracting the appendages,
and eating the goodies on them…
Sea cucumbers have a seemingly suicidal defense
mechanism -- when annoyed, these animals pressurize
themselves and eviscerate violently, forcefully ejecting
their digestive systems, respiratory apparatus, and sexual
glands. The water around them churns with sticky,
mucus-coated innards which tend to damage the gills and
esophagus of the predator which was trying the eat the
cucumber. Unless it is a human…
It regenerates completely in 2-3 weeks…
A Sea Cucumber –an animal, not a salad!
Chordata – the most advanced animal phylum. This
“chord” or backbone provides a framework for the internal
development and structure of the organism. About 5% of the
45,000 species of chordates subsequently lose this chordate
and are called invertebrate chordates; but the other 95% keep
it!
These 95% make up the familiar vertebrate chordates such
as fishes, reptiles, birds and mammals!
Two Invertebrate Chordates of interest are the tunicate (sea
squirt!) and the amphious.
Tunicates – you are related to
these guys…!
The Amphioxus is seen as a link between
invertebrates and vertebrates due to its
notochord and dorsal tubular nervous system
Vertebrate Evolution and Classification
Least successful in
marine environment
Most successful in marine
environment
Class Agnatha - Hagfishes and Lampreys are jawless
fishes which also have no paired fins to help in
locomotion and stabilization.
Their round, sucking mouths are surrounded by
organs sensitive to touch and smell. Their eyes are
degenerate – useless – and covered by thick skin.
Their body ends in a tail that undulates to provide
propulsion. They prefer feeding on the soft, inner
flesh or internal organs of other organisms, and they
use their tongue to “drill” their way in.
There are only about 50 species of these. They make
great pets….
The Charming
Hagfish…
pictures
and a Lamprey
Class Chondrichthyes – includes sharks, rays, skates
and chimaeras. These have been successful for at
least 250 million years (twice as long as dinosaurs!) ,
and they appear not to have changed much in this
time.
All members of this class have a skeleton made of
cartilage – true bone is entirely absent from this
group. They have fins, jaws and teeth… Neither
sharks nor rays have swim bladders, and will slowly
sink if they stop moving.
A Manta Ray – it eats plankton, not divers!
Sharks!
80% of sharks are less than 6 feet long, and only a few of the
remaining 20% are aggressive to humans.
Great Whites are the most dangerous to people. They can be
as big as 23 feet and weigh up to 3,000 pounds.
The largest shark is the Whale Shark. It can be up to 60
feet long and weigh 90,000 pounds. They eat plankton!
Class Osteichthyes – the bony fishes!
27,000+ species are the most numerous of all vertebrates on
the planet! Their numbers include the air-breathing lungfishes
whose ancient relatives broke from the path of evolution to
establish the land vertebrates.
Fish exhibit many advanced characteristics:
• Swim bladders for neutral buoyancy
• Independently movable fins for well-controlled swimming
• Great speed
• Social organization (schooling)
• Migration patterns
The diversity of bony fishes…
It’s tough being a fish..
• Water is about 1000 times as dense as air – it impedes
motion
• Vertical position must always be maintained with minimum
energy expenditure
• Exchange of CO2 and O2 is more complex in a higher
density material
• Osmotic balance, especially in changing salinities
• 3-dimensional range for predators
Movement, shape and propulsion
Eel-like fishes which
use their entire body
length for swimming
are less efficient than
more advanced fishes
which use a “hingedtail” type of motion.
Advanced fishes
Vertical position
• Density of fish tissue is slightly greater than water, so
fish will sink unless their mass is offset by propulsive
forces or buoyant gas- or fat-filled bladders.
• Sharks (and other cartilaginous fishes) must swim to
maintain their position – they generate lift like an airplane
does!
• Swift-swimming fish like tuna and marlin do not have a
swim bladder, because the rapid, high speed depth changes
they experience while chasing prey (or trying to avoid
becoming it) would rupture the bladder as pressure
changed.
Gas Exchange
An active fish like a Mackerel requires so much
oxygen and produces so much CO2 that its gill
surface area must be ten times its body surface area.
Fish extract about 85% of the dissolved oxygen
flowing past their gills (while air breathing
vertebrates extract only about 25%!)
Osmoregulation in freshwater and marine fishes
Feeding and Defense
Passive cryptic
coloration – the
fish looks like a
seaweed blade!
Active cryptic coloration
in a turbot.
Some fish avoid predators by disappearing
completely from the marine environment!
Amphibians (frogs, salamanders & toads)
Only about 2000 living species exist, and none are
exclusively marine (although some large SE Asian frogs can
tolerate salinity up to 28 ppt for extended periods of time.
Sea Turtles –
• may weigh up to 1300 lbs
• Navigate over incredibly long
distances to the beach where they
were originally hatched
• Humans are the only predators!
Hey, dude…
Marine Crocodiles
Only one living species of true marine crocodile – they can
reach 23 feet long and weigh over a ton. They live in Australia
and Indonesia.
Their Louisiana and Florida cousins live in brackish or fresh
water and are much smaller and less dangerous.
Sea Snakes
Probably the most evolutionary
advanced of the marine
reptiles. There are 50 species,
mostly in SE Asia and the
Indian Ocean. None live in the
Atlantic.
With one exception, they give
birth to live young and never
come onto land. All of them
are venomous, and their venom
is among the most powerful
anywhere!
Marine Birds
Birds (class Aves) probably evolved from small, fast running
dinosaurs about 160 million years ago. Their reptilian
heritage is clearly evident in their scaly legs and claws, and
in the arrangement of their internal organs and skeletons.
There are 8,600 living species of birds. They are
endotherms – warm blooded. They have light, thin hollow
bones, and have forsaken heavy teeth and jaws for a
lightweight beak. Only about 3% of birds are “sea birds”,
and most of these live in the southern hemisphere.
True sea birds avoid land except for breeding, and obtain all
of their food from the sea.
The Tubenoses
The Albatross can have a wingspan of 12 feet and a mass of
22 lbs. Their wing structure allows very efficient flight, and
they typically travel up to 9,300 miles on foraging trips.
They see and smell fish, and catch them by dipping their bill
into the water during flight.
Pelicans and their Relatives
Order Pelecaniformes - All of these birds have throat pouches
and webbed feet. They don’t spend as much time over the
open sea as their tubenose relatives. Their wings are adapted
to slow flight. The class includes pelicans, cormorants, frigate
birds, and boobies)
Penguins
Penguins have completely lost the ability to fly, but they use
their reduced wings to swim for long distances and with great
maneuverability. Their “grounded” status makes weight
unimportant, so they have fatty insulation and neutral
buoyancy.
They are native to only
the southern hemisphere
and range in size from a
duck to more than 3.3
feet.
Emperor
Penguins
Mammals
Class Mammalia is the most advanced vertebrate group.
There are about 4,300 species, including humans!
Three groups are:
Cetacea – porpoises, dolphins and whales
Carnivora – seals, sea lions, walruses and sea aotters
Sirenia – manatees and dugongs
Marine Mammal Adaptations
• Streamlined body shape with limbs adapted for
swimming
• They generate internal body heat – large body size favors
smaller surface area to volume ratio (remember cells with
larger surface area to volume ratio…?)
• Lungs and respiratory system adapted to collect and
retain large quantities of oxygen
• They meet their water needs with the metabolic water
derived from the oxidation of food
Some
representatives
from the order
Cetacea (these
are all baleen
whales that feed
on krill)
Toothed whales!
Echolocation, used by toothed whales to locate and
perhaps stun their prey
Baleen plates
A surfacing Blue
Whale with a throat
full of water and food.
California Sea Lion
Harbor Seals
Sea Otters frequently live in or near kelp beds. They have
the densest fur of any mammal!
Polar Bears – an arctic only marine carnivore
And they don’t drink Pepsi…