More Complex
Invertebrate Animals:
Mollusks
Annelids
Arthropods
Echinoderms
I. Mollusks:
• Snails, slugs, conch,
• Mussels, clams, scallops
• Squid, octopus, chambered
nautilus, cuttlefish
I. Characteristics of Mollusks:
• 2nd largest animal phylum
– Arthropoda = largest
• from Latin molluscus, which means “soft.
– Many have soft bodies
– some have a hard shell.
Wide variety of organisms
in this phylum:
• Feeding- Some are sedentary filter feeders
while others are fast-moving predators.
• Nervous system: Some are simple some
are intelligent
• Circulatory system: Gastropoda &
Bivalves have open while Cephalopoda has
a closed system.
Body Cavity:
• Mollusks are true
coelmates.
• Have a body cavity completely
lined by mesoderm tissue layer.
Mollusk Classes
1. Gastropoda
(snails, slugs, albalone, conch)
2. Bivalvia
www.linsdomain.com
(clams, oysters, scallops)
3. Cephalopoda
(octopuses, squid,
cuttlefish, chambered
nautiluses)
www.mcaorals.co.uk
www.iptek.net.id
1. Class Gastropoda
• The largest & most diverse class of mollusks
• Most have a single
shell.
– including snails, abalones, limpets and conchs.
– Slugs have no shell.
• Open circulatory system in which a
heart pumps hemolymph from gills or lungs
into the hemocoel (body cavity)
Mollusk Gastropod Body Plan
• Divided into 2 main parts:
– Visceral mass
• which contains the heart and the organs of digestion, excretion, and
reproduction
– Head-foot, which consists of:
• the head, contains the mouth with Radula– a tongue like feeding adaptation with tiny teeth that point
backwards) and sensory structures
• the foot, a large, muscular organ for locomotion
• Other parts:
– Coelom -limited to space around heart.
– Mantle -a layer of epidermis that covers the visceral mass.
(secretes the shell)
Gastropod body
Mollusk class: Gastropoda,
snails
static.blogr.com
www.dpughphoto.com/mollusks.htm
Phylum: Mollusk
Class: Gastropoda
Animal: Common garden slug
www.ppdl.org/dd/id/slugs.html
Conch shell
http://en.wikipedia.org/wiki/Conch
2. Class Bivalvia
• Aquatic mollusks (clams,
oysters, & scallops)
• Shell is divided into two
valves connected by a
hinge.
• Most are sessile filter
feeders.
• Bivalves lack a distinct
head
Clams
• The mantle cavity of a clam is sealed except for a
pair of hollow, fleshy tubes called siphons.
– Water enters through the incurrent siphon.
– Water leaves through the excurrent siphon.
Other Bivalves
• Oysters attach to a hard surface
• Scallops can move through the water by repeatedly
opening their valves and snapping them shut.
3. Class Cephalopoda
• Means “head-foot.”
• Free-swimming
predators
• Have tentacles &
beaklike jaws on the
head.
• Also- Have a closed
circulatory system.
Squids
• 10 tentacles.
• Propels by pumping jets of water with the mantle
through an excurrent siphon.
Octopuses
• 8 tentacles
• They often crawl along the ocean bottom or lie in
wait for prey.
Chambered Nautiluses
• The only existing cephalopod with external shell.
• Shell is coiled & divided into chambers.
• The body is confined to the outermost chamber.
Caribbean reef squid (Venezuela)
Displays an aggressive zebra pattern to ward off other males
competing for nearby females. This vivid species can display
about three dozen different color patterns. (National Geographic)
In a cloud of greenish ink, a
jumbo squid flees!
National geographic
If all their dazzling color changes fail to deter a predator, squid use ink
as a backup defense that helps them fade from view. Mexican
fishermen catch some 100,000 tons (90,000 metric tons) of jumbos a year
Huge eye of the world's largest squid
• About 11 inches
across, researchers
believe the colossal
squid's eye is the
biggest animal eye
ever found.
• The 10m-long (34ft)
specimen has also
turned out to be female.
• Very little is known about colossal squid; only about 10 have ever
been caught and brought to shore.
www.enricobaccarini.com/.../eyesquid.htm
The giant squid
• remains largely a mystery to scientists
despite being the biggest invertebrate on
Earth.
• largest of these elusive giants ever found
measured 59 feet (18 meters) in length and
weighed nearly a ton (900 kg).
Small Squid (Calamari)
Kalamarakia (discovergreek food.com)
Caribbean reef octopus
hunting, making a balloon and scaring little fish out from under
rocks to become dinner. Octopus briareus
dive.scubadiving.com
An octopus swimming; an octopus
moving between tide pools
http://en.wikipedia.org/wiki/Octopus
• But Octopus are
tasty too!!!
Charred Octopus With Garlic,
Chilli, Lemon And Oliveau.lifestyle.yahoo.com
Oil
GRILLED BABY OCTOPUS
WITH WATERCRESS SALAD &
ORANGES
A recipe by Chef Doug D’Avico
www.italian-food-lovers.com
A chambered Nautilus
www.math.tamu.edu
The Chambered Nautilus:
In which nature flawlessly executes constant
mathematical form (It’s a physics thing)
http://en.wikipedia.org/wiki/Anthropic_principle.
(Photo by John Lienhard)
http://www.uh.edu/engines/chamberednautilusform.jpg
Very Intelligent invertebrates:
• Nervous system is very advanced.
EXAMPLES:
• Dexterity, tool use and manipulation. Suction
cups & arms are as efficient as human’s hand.
• Can learn through observation (choose colored
balls)
• Can “Hide” & act like sea weed,
• Assess their prey.
• Complete & remember mazes & patterns
http://en.wikipedia.org/wiki/Cephalopod_intelligence ,
http://www.fortunecity.com/emachines/e11/86/cephpod.html
Many Cephalopods use pigments to
hide & disguise themselves.
Blue-ringed octopus (size of a plum) this beak packs a
deadly poison that'll kill a human in about 15 minutes.
Octopuses have blue “blood”
• Octopuses have three hearts.
• Its blood has copper-rich protein (blue)
hemocyanin for transporting oxygen.
– Although less efficient under normal conditions than the ironrich hemoglobin of vertebrates, in cold conditions with low
oxygen pressure, hemocyanin oxygen transportation is more
efficient than hemoglobin oxygen transportation.
• The hemocyanin is dissolved in the plasma instead of
being bound in red blood cells and gives the blood a blue
color.
Octopuses: short life expectancy
• some live for as little as six months. Larger
species, such as the North Pacific Giant Octopus,
may live for up to five years
• However, reproduction is a cause of death:
– males can only live for a few months after mating
– females die shortly after their eggs hatch.
• They neglect to eat during the (roughly) one month period
spent taking care of their unhatched eggs, but they don't die
of starvation.
• Endocrine secretions from the two optic glands are the cause
of genetically-programmed death
Links
• http://video.nationalgeographic.com/video/p
layer/animals/invertebratesanimals/octopus-and-squid/
• http://ngm.nationalgeographic.com/ngm/04
08/feature2/zoom1.html
II. Phylum Annelida
Segmented worms:
• Earthworm
• Bristle worms
• Leeches
Segmented worms: Annelids
• Annelids means little rings (many body
segments).
• True coelom animals: have a body cavity that is divided
into separate compartments by partitions.
Other terms:
• Most have external bristles called setae
• Some have fleshy protrusions called parapodia
Class Oligochaeta
• Live in the soil or in fresh water
• Most familiar is the earthworm.
Structure and Movement
• An earthworm’s body has over 100 nearly-identical
segments.
• Circular and longitudinal muscles line
the interior body wall.
• Locomotion is made possible by segmentation.
Earthworms
www.separationsnow.com
Earthworms Feeding /Digestion
Ingest soil as they burrow through it.
• Soil is moved through these structures:
– mouth
– pharynx
– esophagus
– crop
– gizzard
– intestine
– anus
• Earthworms play an important role in the condition of soil.
Closed circulatory system.
• Contractions of the aortic arches and the dorsal blood
vessel force blood through the vessels of the body
Respiration and Excretion
• Oxygen and carbon dioxide diffuse through moist skin,
• Cellular wastes and excess water are excreted through
nephridia.
Neural Control
• Consists of a chain of ganglia connected by a ventral nerve
cord.
• Sensory structures are found in all segments but are
concentrated at the anterior end.
Reproduction
• Earthworms are hermaphrodites, but an
individual worm cannot fertilize its own eggs.
• During mating, earthworms press their ventral
surfaces together.
• Held together by their setae and by a film of mucus
secreted by each worm’s clitellum.
• Fertilization occurs inside the tube, which forms a
protective case for the young worms.
Earthworms reproducing
http://upload.wikimedia.org/wikipedia/commons/thumb/9/97/Earthworm
_klitellum_copulation_beentree.jpg/800px-Earthworm_klitellum_copulation_beentree.jpg
Earthworm diagrams
Earthworm links:
• http://www.urbanext.uiuc.edu/worms/facts/in
dex.html
• http://animals.nationalgeographic.com/animal
s/invertebrates/earthworm.html
Class
Polychaeta
“many bristles” “feather duster worms”
•
• Polychaetes differ from other annelids in that they have
antennae & specialized mouthparts.
Class Hirudinea
• Hirudinea is the smallest class, consisting of about 500
species of leeches.
• Leeches -have no setae or parapodia.
• Many leeches are carnivores but some are parasites that
suck blood from other animals.
Haemophagic Leeches
• Attach to their hosts & remain until they
become full & they fall off to digest.
• Bodies are 34 segments.
• Have an anterior (oral) sucker formed
from the first six segments of their body,
used to connect to a host for feeding and
releases an anaesthetic to remain
unnoticed by the host.
• Use a combination of mucus and suction
to stay attached and secrete an anticlotting enzyme into the host's blood
stream.
• http://en.wikipedia.org/wiki/Leech
Leeches:
www.fcps.edu
http://en.wikipedia.org/wiki/Leech
Famous Film Moment for leeches:
Humphrey Bogart in
The African Queen
http://img.metro.co.uk/i/pix/2008/07/Bogart180708_450x302.jpg
How
to
Remove
and
Treat
Leech
Bites
Find the skinny end [the head end]
and use your finger or fingernail to
push it sideways off the bite point."
- Authority Mark Siddall in the
NOVA Science Internet site.
You should avoid "remedies" such
as simply pulling the leech from its
moorings; plying it with salt, insect
repellent, shampoo or vinegar; or
heating it with a smoldering match,
grass stem or cigarette. These
techniques might cause the leech
to discharge the contents of its gut,
including bacteria, into the
bite. This might cause
complications such as localized
infection or even blood poisoning.
www.desertusa.com/mag08/sept08/leeches.html
Leeches and a History of Medicine
www.leeches.biz/medicine-leech.htm
• For over 4000 years, the
leech has been a
familiar remedy, with
Greek and Roman
physicians praising the
application of this
clever invertebrate.
In the 19th century leeches
• were enjoying a golden age.
• Millions were raised for medical use as their fame
as a cure-all ensued.
• The mid 1800s saw their constant use for local
bloodletting. Druggists administered thousands of
leeches to patients with anything from gumboils to
facial discoloration.
• They were also put inside the mouth.
Leeches Today
• are bred in captivity in many institutions.
• Leeches have found new fame in microsurgery,
where doctors require the precision of the leech to
drain congested blood from wounded sites.
• Plastic surgeons are particularly grateful for the
contribution made by the leech, due to their use in
the treatment of difficult grafts and reconstructive
surgery.
III. Arthropods &
Insects
“The real rulers of the Earth”
Sources used include textbook, (Holt Modern Biology)
http://www.ucmp.berkeley.edu/arthropoda/arthropoda.html
http://evolution.berkeley.edu/evolibrary/article/_0_0/arthropods_intro_01
More than 83% of all animal
species are arthropods.
• That's about 160 million insects for
each person on Earth.
• Have evolved to fill a variety of
ecological niches — from tiny internal
parasite to giant bird-eating predator.
• Arthropods are a lot more than just
delicious feasts and disgusting pests
5 Characteristics of all
Arthropods
Segmented Body
• Each segment repeats the same set of structures
(ie, a pair of legs, a set of breathing organs, & a set of nerves),
• sets of segments are grouped into a larger unit,
such as the abdomen & cephalothorax.
Hard
Exoskeleton
Made of protein & Chitin (a polysaccharide)
•
• Must molt many times as grows
• Enzymes digest the layer of exoskeleton inside soften &
then shed. It takes a few days for the newly excreted
exoskeleton to harden.
Jointed Legs
• All arthropods (arthro = joint, pod =
foot) have jointed limbs.
• How can an animal with a rigid body
covering move its legs?
• The exoskeleton is hard, but at the
joints it is softer & bendable, (allowing
movement in same way a suit of armor
does).
Many pairs of limbs
• Tagma- are specialized segments
The five major subphyla of the
phylum Arthropoda.
Arthropods usually
divided into 5
subphyla based
on:
– differences in
development
– in the structure
of appendages,
such as
mouthparts.
1. Trilobites
• Extinct
• Many body appendages with one
pair of appendages per segment
• Trilobites, living in shallow seas, flourished as
swimmers, crawlers and burrowers for some
350 million years.
• Fossils found on all continents, entrapped in
the hardened sediments of Ancient Seas.
http://www.trilobite.com/
2. Subphylum
Myriapoda
• Means”many feet”
• One pair of branched antennae
• Many body segments
• Includes classes:
– Diplopoda (millipedes)
• Up to 100 body segments
• 2 pairs of legs on each segment
– Chilopoda (centipedes)
• In tropical regions can reach 12 inches long
• From 15 to 175 pairs of legs
3. Subphylum Crustacea
• about 38,000 known species.
• Terrestrial & Marine
• so diverse their single defining characteristic is having two
pairs of antennae.
• Most also have:
– a pair of mandibles
– a pair of appendages on
each body segment
– some branched appendages
– 16 to 20 segments &
– several tagmata
http://copepodes.obs-banyuls.fr/images/NAUPLIUS.jpg
a. Terrestrial Crustaceans
• Sow bugs and pill bugs are terrestrial isopods.
• They lack adaptations for conserving water and live
only in moist environments.
• They generally feed on decaying vegetation.
• Pill bugs roll into a ball when disturbed or threatened.
b. Aquatic Crustaceans (many species)
• Copepods -important part of the
ocean’s plankton.
• In freshwater, much of the plankton
are water fleas such as Daphnia
species.
• Barnacles are sessile as adults.
www.divediscover.whoi.edu
www.microscopyu.com
– Free-swimming barnacle larvae attach to surfaces
and develop a shell that encloses the body.
– Barnacles use their cirri (singular, cirrus) to
sweep food.
www.ryanphotographic.com
Types of barnacles
http://www.marinebio.net/marinescience/03ecology/tphi.htm
Balanus Barnacle with legs out,
filter feeding on plankton
Gooseneck Barnacles
More aquatic crustaceans
• Order Decapoda -means“10 feet”
• Decapods have five pairs of legs
• Crayfish, lobsters, crabs, and shrimp are
decapods
• Respiration through gills
• (see more about crayfish in handout & know parts
for dissection lab)
4. Subphylum Chelicerata
• Defined by presence of chelicerae
– The first pair of appendages
– Modified into pincer or fangs
• Class Arachnid- spiders, scorpions, mites, ticks
• Some important Parts :
– Chelicerae ( in spiders = fangs to inject poison)
– Pedipalps (hold food)
– 8 simple eyes at anterior of cephalothorax (NOT compound eyes!)
– Spinnerets- 3 pairs on tip of abdomen, for making silk
– Book lungs- like folds in a book= lots of surface area for gas exchange
(some spiders use Tracheae for respiration instead)
– Malpighian Tubes- excretory tubes collect wastes, liquids. The liquid is
reabsorbed (to conserve water) & waste is nearly solid.
Spiders-A full facial view of any
spider shows its killing ability.
• Two powerful chelicerae, protrude down
• Each chelicera bears a hinged fang.
• Both fangs have ducts that lead up to the venom glands
within the head.
• Spiders fall into two groups, each being classified upon
how they strike their prey.
– The fangs of Tarantulas are so hinged that they articulate in a
front-to-back motion allowing them to strike their prey from
above.
– Most other spiders have fangs that are hinged laterally, providing a
left-to-right strike.
www.microscopix.co.uk/spiders/fangs/index.htm
Spider Chelicerae
Fangs and Chelicerae of
Tarantula Spiderling
Brachypelma smithi
(Mexican Red-Knee Tarantula)
Fangs, Chelicerae of Zebra Jumping Spider
Salticus scenicus
www.microscopix.co.uk/spiders/fangs/index.htm
Anatomy of a spider
** Mites and ticks differ from spiders because they
have a fused cephalothorax and abdomen.
Life of a Spider
• Spiders feed on insects and other small animals.
Many species are adapted to capture certain prey.
• Spiders rarely harm humans, but two species in
the United States are dangerous:
– the black widow
– the brown recluse
• A male spider is usually smaller than the female.
• Females lay eggs in a silken case.
Brown recluse
http://www.lib.uiowa.edu/hardin/md/pictures22/dermatlas/loxosceles_1_020724.jpg
http://upload.wikimedia.org/wikipedia/commons/9/99/Brown_recluse_spider,_Loxosceles_reclusa.jpg
Black widow spider
http://www.spidy.goliathus.com/img/BlackWidowSpider.jpg
“Daddy long legs”
Pholcus phalangioides – a real “spider”
Harvestmen (Phalangium opili)
• Harvestmen are different from spiders:
- in harvestmen the two main body sections (the abdomen with ten segments
and cephalothorax) are nearly joined, so that they appear to be one oval
structure;
- they also have no venom or silk glands.
- Mouth is different so that ingestion is not restricted to liquid, but chunks
of food can be taken in.
- They have a single pair of eyes in the middle of their heads
http://en.wikipedia.org/wiki/Opiliones
Daddy long legs urban legend
• Claims are that the harvestman is the most
venomous animal in the world, but its fangs are
too small to bite a human and therefore is not
dangerous.
• This is untrue on several counts.
– None of the known species have venom glands or fangs
– The size of its mouth varies by species, but even those
with relatively large jaws hardly ever bite humans or
other large creatures, even in self-defense.
– The few known cases of actual bites did not involve
envenomation, and had no lasting effect
http://en.wikipedia.org/wiki/Opiliones
Giant sea spider- new finds in
Antarctica
• Video link:
http://news.nationalgeographic.com/news/2008/02/0802
19-spider-video-ap.html
http://www.spaceref.com/news/viewpr.html?pid=9218
Camel spider “Urban legend”
• Comments: NOT TRUE!!
• This scary-looking creature (actually, it's a pair of scary-looking
creatures dangling end-to-end) is indeed commonly called a camel
spider, but in fact it is neither a spider, strictly
speaking (entomologists call it a solifugid), nor
is it found only in the Middle East. Camel
spiders reside in arid locales all over the world,
including the southwestern United States.
• A typical specimen can grow to about the size of a child's hand, but,
though they are known for being vicious predators, camel spiders
are neither venomous nor a threat to human beings.
• For the record, they don't eat camels, either.
Common house spiders
Excellent site to look up spiders!!
• http://www.spiderzrule.com/wind.
htm
• http://www.spiderzrule.com/com
monspidersusa.htm
5. Subphylum Hexapoda
• Class Insecta
• By many standards- the most successful group of
animals on earth.
• Entomology- the study of insects & terrestrial
arthropods.
• Body of an insect is divided into
tagmata:
– Head
– Thorax
– Abdomen
3
“bugs”
• Because they dominate all terrestrial
environments that support human
life, insects are usually our most
important competitors for food,
fiber, and other natural resources.
Grasshopper
• Example organism
• Please note parts for dissection lab,.
The crayfish- next 4 pages are notes
for dissection lab
• an abundant freshwater crustacean that is
structurally similar to lobsters, which are
marine crustaceans.
• Crayfish, lobsters, crabs, and shrimp are
decapods, or members of the order Decapoda.
Decapoda means “10 feet.”
• Decapods have five pairs of legs that are used
for locomotion.
External Structure
• The crayfish’s body is divided into
– the cephalothorax, which is covered by the carapace and
is divided into
• the head, which has five segments
• the thorax, which has eight segments
– the abdomen, which is is divided into six segments
• A pair of appendages is attached to each segment of the crayfish.
Several pairs have specialized functions.
• These appendages include:
–
–
–
–
–
–
–
–
Antennae
Antennules
Mandibles
Maxillae
Maxillipeds
Chelipeds
Walking legs
Swimmerets
Crayfish -Parts for lab
Excretion
• Green glands assist in excretion of excess water that enters the
body by osmosis.
Digestion
• Digestive gland near the stomach secretes enzymes for
digestion.
Respiration
• gills.
Circulation
• open.
Nervous & Sensory Organs
• Many small sensory hairs. (sense water vibrations & chemicals)
Compound eyes are set on two stalks.
Insects
• Entomologists classify insects into more than 25
orders based on characteristics such as:
– structure of mouthparts
– number of wings
– type of development
Factors responsible for their success include:
–ability to fly
–jointed appendages
–large numbers offspring
-exoskeleton
-small size
-short life span
Just how dominant are insects?
Comparison of 2 of the 5 groups of
Arthropods
Insects as Food
•
•
Insects are an important source of nutrition in many parts of the world
In Mexico, dried grasshoppers are sold in village markets. High in protein and low
in fat, they may be fried or ground into meal and mixed with flour to make tortillas.
• Sago grubs, the larvae of a wood-boring beetle, are considered a delicacy in Papua
New Guinea. The islanders boil the larvae or roast them over an open fire.
• Ants, bees, termites, caterpillars, water bugs, beetle larvae, flies, crickets, katydids,
cicadas, and dragonfly nymphs are among a long list of edible insects that provide
nutrition for the people of Australia, Africa, South America, the Middle East, and
China.
• Americans and western Europeans
appear to be unique in having a strong
cultural taboo against insects as food.
•
Silkworm pupae for
human food in
Thailand
•http://www.cals.ncsu.edu/course/ent425/text01/index.html
A Recipe for Maggot Crispies
• 1/4 cup margarine
4 cups small marshmallows
3 cups crispy cereal
3 cups dry roasted maggots or mealworms
In a saucepan, melt margarine and
marshmallows. Remove from heat and stir
in cereal and maggots. Spread mixture in a
9x13 greased pan and allow to cool.
Insect body –
is divided into three tagmata:
1. Head -has mandibles and one pair of
unbranched antennae.
2. Thorax -has three pairs of jointed legs and,
in many species, one or two pairs of wings.
3. Abdomen -has 9 to 11 segments but
neither wings nor legs in adults.
Humans & insects:
• Used for consumer
• Example:
products too:
cochineal
“Today, the textile industry has largely replaced
cochineal with less expensive aniline dyes, but
it is still used as a coloring agent in foods,
beverages, cosmetics (especially lipsticks), and art
products.”
http://www.cals.ncsu.edu/course/ent425/text01/impact1.html
Got Bugs? http://www.foxnews.com/story/0,2933,479233,00.htmlm
• GOT WAFFLES, LIPSTICK, YOGURT OR STRAWBERRY
MILK? HOW ABOUT CANDY, SHAMPOO AND NAIL
POLISH?
• THE FDA SAYS SCATTERED ALLERGIC REACTIONS
ARE THE BASIS FOR THE RULE CONCERNING DYE
DERIVED FROM THE CRUSHED COCHINEAL BUG.
• UNKNOWN AND UNNOTICED BY MOST CONSUMERS,
THE JUICE OF A TINY BEETLE FIRST USED BY 16TH
CENTURY SPANISH EXPLORERS IS RESPONSIBLE FOR
RED, PINK, ORANGE AND PURPLE COLORING IN
HUNDREDS OF U.S. PRODUCTS.
• NOW, THE FOOD AND DRUG ADMINISTRATION HAS
DECIDED TO MAKE FOOD AND COSMETIC
MANUFACTURERS IDENTIFY THE BUGGY SOURCE OF
CARMINE OR COCHINEAL EXTRACT, WHICH MAY BE
IDENTIFIED ONLY AS "COLOR ADDED" IN A
PRODUCT'S LIST OF INGREDIENTS.
Insects and People
• Insects negatively affect humans by:
– competing for food
– transmitting diseases
– destroying buildings & other manufactured products
• Insects benefit humans by:
–
–
–
–
serving as food for other animals
pollinating flowers
making valuable products such as honey
recycling nutrients in ecosystems
External Anatomy Grasshopper
Internal Anatomy Grasshopper
Grasshopper body- three tagmata:
– The head
• mouthparts -labrum & labium are mouthparts that function
like upper and lower lips, respectively.
• a pair of unbranched antennae
• pairs of simple and compound eyes.
– The thorax is composed of:
• Prothorax
• Mesothorax
• Metathorax
– The
abdomen has upper and lower plates
Insect mouthparts
Circulation, Respiration, & Excretion
• Insects have an open circulatory system
that transports nutrients through the body.
• Gas exchange occurs by means of air-filled
tracheae that reach deep into the body.
• Malpighian tubules remove cellular wastes
from the hemolymph while conserving water.
Nervous system
• The grasshopper’s central nervous system consists of
a brain and a ventral nerve cord with
ganglia located in each body segment.
• Nerves extend from the brain to sensory structures.
• Insect sensory structures include :
– simple and compound eyes
– sensory hairs on antennae and other body parts
– in some species, a sound-sensing tympanum
Reproduction
• Grasshoppers have separate sexes,
– as do all insects.
• During mating, the male deposits sperm into
the female’s seminal receptacle, where the
eggs are fertilized internally.
• The last segment of the female’s abdomen
forms the ovipositor, which she uses to lay
fertilized eggs.
Most insects go through
metamorphosis.
• In incomplete metamorphosis, a nymph
hatches from an egg and resembles the adult but has
undeveloped reproductive organs and no wings. The
nymph molts several times to become an adult.
• In complete metamorphosis, a wormlike larva
called a caterpillar hatches from an egg and
molts several times before becoming a pupa. The
pupa molts to produce the adult, which resembles
neither the larva nor the pupa.
Incomplete vs. Complete metamorphosis
Complete metamorphosis
-allows larvae and adults of the same species to avoid competing
for space and food.
-allows survival in periods of harsh weather or scant resources.
IV. Echinoderms
(Last phyla of invertebrates)
• Starfish
• Sand Dollars
• sea urchins
• sea stars
• Brittle stars
• Sea cucumbers
Echinoderms
• are all benthic (bottom-dwellers)
• endoskeleton of interlocking calcium
carbonate plates and spines
• All true coelomates
• Nervous systems are poorly developed
• lack respiratory systems & circulatory
systems (the water-vascular system takes
over some of the functions of these systems)
Echinoderms
• water-vascular system of special structures that protrude &
help the echinoderm breath, move, and defend itself.
– tube feet
– pedicellaria
– gills
• All echinoderms have a, a set of water-filled canals branching
from a ring canal that encircles the gut. The canals lead to
podia, or tube feet, which are sucker-like appendages that the
echinoderm can use to move, grip the substrate, or manipulate
objects. These tube feet are extended and retracted by
hydraulic pressure in the water-vascular system.
Feeding:
•
•
•
•
Some, like many starfish, are predators
sand dollars often feed on detritus
crinoids are filter-feeders
sea urchins scrape algae from rocks
Reproduction
• External fertilization; eggs and sperm are freely
discharged into the water.
• A few sea urchins brood their eggs in special
pouches, but most provide no parental care.
• Most echinoderms go through several planktonic
larval stages before settling down