Transcript Invertebrates - Des Moines Area Community College, Iowa

Chapter 33
Invertebrates
Let’s meet the … Invertebrates
Life Without a Backbone

Invertebrates
 Are
animals that lack a backbone
 Account for 95% of known animal species
Xmas Tree
Worm
Eumetazoa
Ancestral colonial
choanoflagellate
Chordata
Echinodermata
Other bilaterians (including
Nematoda, Arthropoda,
Mollusca, and Annelida)
Cnidaria
Porifera
A review of animal phylogeny
Deuterostomia
Bilateria
Invertebrate diversity
PORIFERA (5,500 species)
A sponge
PLACOZOA (1 species)
CNIDARIA (10,000 species)
A jelly
KINORHYNCHA (150 species)
0.5 mm
250 µm
A placozoan (LM) A kinorhynch (LM)
ROTIFERA (1,800 species)
PLATYHELMINTHES (20,000 species)
A marine flatworm
ECTOPROCTA (4,500 species)
A rotifer (LM)
PHORONIDA (20 species)
Ectoprocts Phoronids
Invertebrate Diversity
BRACHIOPODA (335 species)
A brachiopod
ACANTHOCEPHALA (1,100 species)
NEMERTEA (900 species)
A ribbon worm
CTENOPHORA (100 species)
5 mm
An acanthocephalan
MOLLUSCA (93,000 species)
A ctenophore, or comb jelly
ANNELIDA (16,500 species)
An octopus
LORICIFERA (10 species)
A marine annelid
PRIAPULA (16 species)
50 µm
A loriciferan (LM)
A priapulan
Invertebrate Diversity
ARTHROPODA (1,000,000 + species)
NEMATODA (25,000 species)
A roundworm
A scorpion (an arachnid)
CYCLIOPHORA (1 species)
TARDIGRADA (800 species)
100 µm
100 µm
A cycliophoran (colorized SEM) Tardigrades (colorized SEM)
HEMICHORDATA (85 species)
ONYCHOPHORA (110 species)
An onychophoran
An acorn worm
ECHINODERMATA (7,000 species)
A sea urchin
CHORDATA (52,000 species)
A tunicate
Sponges (Phylum Porifera)

Sponge characteristics
 Sessile
 Porous
body
 Choanocytes: flagellated collar cells generate a water current
through the sponge and ingest suspended food by phagocytosis
 Live
in both fresh and marine waters
 Lack true tissues (groups of similar cells that form a functional
unit). All animals except sponges belong to the clade
Eumetazoa, the animals with true tissues
 Most sponges are hermaphrodites (each individual functions
as both male and female)
Sponges

Sponges are suspension feeders

Capturing food particles suspended in the water that passes
through their body
5 Choanocytes. The spongocoel
is lined with feeding cells called
choanocytes. By beating flagella,
the choanocytes create a current that
draws water in through the porocytes.
Azure vase sponge (Callyspongia
plicifera)
4 Spongocoel. Water
passing through porocytes
enters a cavity called the
spongocoel.
3 Porocytes. Water enters
the epidermis through
channels formed by
porocytes, doughnut-shaped
cells that span the body wall.
2 Epidermis. The outer
layer consists of tightly
packed epidermal cells.
1 Mesohyl. The wall of this
simple sponge consists of
two layers of cells separated
by a gelatinous matrix, the
mesohyl (“middle matter”).
Flagellum
Collar
Food particles
in mucus
Choanocyte
Osculum
Phagocytosis of
food particles
Spicules
Water
flow
Amoebocyte
6 The movement of the choanocyte
flagella also draws water through its
collar of fingerlike projections. Food
particles are trapped in the mucus
coating the projections, engulfed by
phagocytosis, and either digested or
transferred to amoebocytes.
7 Amoebocyte. Amoebocytes
transport nutrients to other cells of
the sponge body and also produce
materials for skeletal fibers (spicules).
Cnidarians (Phylum Cnidaria)


A diverse range of both
sessile and floating
organisms including
hydras, jellies, sea
anemones, and corals
Cnidarian characteristics



radial symmetry
gastrovascular cavity
(digestive compartment)
Cnidocytes
movie
Cnidarian Body Plan




Relatively simple diploblastic (two germ layers), radial body plan
Basic body plan of a cnidarian is a sac with a central digestive compartment, the
gastrovascular cavity
A single opening functions as both mouth and anus
There are two variations on this body plan

The sessile polyp and the floating medusa
Polyp
Medusa
Mouth/anus
Tentacle
Gastrovascular
cavity
Gastrodermis
Mesoglea
Body
stalk
Epidermis
Tentacle
Mouth/anus
Cnidarian Feeding

Cnidarians are carnivores
 That

use tentacles to capture prey
The tentacles are armed with cnidocytes
 Unique
cells that function in defense and the
capture of prey
Tentacle
Threads can inject
poison into the prey, or
stick to or entangle the
target
“Trigger”
Discharge
Of thread
Nematocyst
Coiled thread
Cnidocyte
Prey
Classes of Phylum Cnidaria
Hydrozoan Life Cycle
2 Some of the colony’s
polyps, equipped with tentacles,
are specialized for feeding.
3 Other polyps, specialized
for reproduction, lack
tentacles and produce tiny
medusae by asexual budding.
4 The medusae
swim off, grow, and
reproduce sexually.
Reproductive
polyp
1 A colony of
interconnected
polyps (inset,
LM) results
from asexual
reproduction
by budding.
Feeding
polyp
Medusa
bud
MEIOSIS
Gonad
Medusa
SEXUAL
REPRODUCTION
Sperm
Egg
ASEXUAL
REPRODUCTION
(BUDDING)
Portion of
a colony
of polyps
FERTILIZATION
Zygote
Developing
polyp
Mature
polyp
Planula
(larva)
1 mm
6 The planula eventually settles
and develops into a new polyp.
5 The zygote develops into a
solid ciliated larva called a planula.
Key
Haploid (n)
Diploid (2n)
Classes: Hydrozoa, Scyphozoa, Cubozoa,
and Anthozoa
(b) Many species of jellies (class
Scyphozoa), including the
(a) These colonial polyps are members of
class
Hydrozoa.
species pictured here, are
bioluminescent. The largest
scyphozoans have tentacles
more than 100 m long
dangling from a bell-shaped
body up to 2 m in diameter.
(c) The sea wasp (Chironex
fleckeri) is a member of
class Cubozoa. Its poison,
which can subdue fish and
other large prey, is more
potent than cobra venom.
(d) Sea anemones and other
members of class Anthozoa
exist only as polyps.
Cnidarian Classes

In the class Hydrozoa
 Most hydrozoans alternate between polyp and medusa forms.
Freshwater Hydras exist only in the polyp form.

In the class Scyphozoa
 Jellies (medusae) are the prevalent form of the life cycle

In the class Cubozoa, which includes box jellies and sea wasps
 The medusa is box-shaped and has complex eyes

Class Anthozoa includes the corals and sea anemones
 Which occur only as polyps
Purple
coral
Hydra
Hydra movie 1
Hydra movie 2
Coral reproduction
Jellyfish movie
Bilateria
Most animals have bilateral symmetry
 The vast majority of animal species belong
to the clade Bilateria

 Which
consists of animals with bilateral
symmetry and triploblastic development
Flatworms

Members of phylum Platyhelminthes
 Live
in marine, freshwater, and damp terrestrial
habitats. Some are parasitic.
 Are flattened dorsoventrally and have bilateral
symmetry
 Undergo triploblastic development
 Are acoelomates (lack a coelom) with gastrovascular
cavities.
 Lack a digestive system entirely and absorb
nutrients across their body surface.
Flatworm Classes
Turbellarians

Are nearly all free-living and mostly marine
Turbellarians

Planarians are common examples of
turbellarians
 They
have light-sensitive eyespots and centralized
nerve nets
Pharynx. The mouth is at the
tip of a muscular pharynx that
extends from the animal’s
ventral side. Digestive juices
are spilled onto prey, and the
pharynx sucks small pieces of
food into the gastrovascular
cavity, where digestion continues.
Digestion is completed within
the cells lining the gastrovascular cavity, which has
three branches, each with
fine subbranches that provide an extensive surface area.
Undigested wastes
are egested
through the mouth.
Gastrovascular
cavity
Eyespots
Ganglia. Located at the anterior end
of the worm, near the main sources
of sensory input, is a pair of ganglia,
dense clusters of nerve cells.
Ventral nerve cords. From
the ganglia, a pair of
ventral nerve cords runs
the length of the body.
Monogeneans and Trematodes



Live as parasites in or on
other animals They
parasitize a wide range of
hosts
Most monogeneans are
parasites of fish
Trematodes (Flukes) that
parasitize humans spend
part of their lives in snail
hosts
1 Mature flukes live in the blood vessels of the human
intestine. A female fluke fits into a groove running
the length of the larger male’s body, as shown in
the light micrograph at right.
Male
Female
1 mm
5 These larvae penetrate
the skin and blood
vessels of humans
working in irrigated
fields contaminated
with infected human
feces.
2 Blood flukes reproduce
sexually in the human host.
The fertilized eggs exit the
host in feces.
3 The eggs develop in
water into ciliated
larvae. These larvae
infect snails, the
intermediate hosts.
4 Asexual reproduction
within a snail results in
another type of motile
larva, which escapes from
the snail host.
Snail host
Tapeworms (Class Cestoda)
 Are
also parasitic and lack a digestive system
Proglottids with
reproductive structures
200 µm
Scolex
Hooks
Sucker
Rotifers (Phylum Rotifera)


Are tiny animals that inhabit fresh water, the ocean, and damp soil
Rotifers are smaller than many protists


Rotifers have an alimentary canal


But are truly multicellular and have specialized organ systems
A digestive tube with a separate mouth and anus that lies within a fluid-filled pseudocoelom
Some species of rotifers reproduce by parthenogenesis

In which females produce more females from unfertilized eggs
0.1 mm
Rotifers (Phylum Rotifera)
Rotifer movie 2
Three Phyla of Lophophorates:
Ectoprocts, Phoronids, and
Brachiopods

Lophophorates have a lophophore
 A horseshoe-shaped,
suspension-feeding
organ bearing ciliated tentacles that trap
suspended food particles
Ectoprocts
Are colonial animals that superficially resemble
plants
Lophophore
(a) Ectoprocts, such as this sea
mat (Membranipora
membranacea), are colonial
lophophorates.
Phoronids
 Are
tube-dwelling marine worms ranging from 1 mm
to 50 cm in length
Lophophore
(b) In phoronids such as
Phoronis hippocrepia, the
lophophore and mouth
are at one end of an
elongated trunk.
Brachipods

Superficially resemble clams and other hingeshelled molluscs
 But
the two halves of the shell are dorsal and ventral
rather than lateral, as in clams
Lophophore
(c) Brachiopods have a hinged shell.
The two parts of the shell are
dorsal and ventral.
Nemerteans (Phylum Nemertea)


Commonly called proboscis worms or ribbon worms
The nemerteans unique proboscis



Is used for defense and prey capture
Is extended by a fluid-filled sac
Nemerteans also have a closed circulatory system

In which the blood is contained in vessels distinct from fluid in the body
cavity
Molluscs (Phylum Mollusca)


Phylum Mollusca: Includes snails and slugs, oysters and
clams, and octopuses and squids
Mollusc characteristics


Body plan: muscular foot, visceral mass, and a mantle
Mantle is a fold of tissue that drapes over the visceral mass and
secretes the shell.
 Most molluscs are marine, though some inhabit fresh water and
some are terrestrial
 Molluscs are soft-bodied animals, but most are protected by a
hard shell
 Most molluscs have separate sexes with gonads located in the
visceral mass
 The life cycle of many molluscs includes a ciliated larval stage
called a trochophore
Mollusc anatomy
Nephridium. Excretory organs
called nephridia remove metabolic
wastes from the hemolymph.
Heart. Most molluscs have an open circulatory
system. The dorsally located heart pumps
circulatory fluid called hemolymph through arteries
into sinuses (body spaces). The organs of the
mollusc are thus continually bathed in hemolymph.
The long digestive tract is
coiled in the visceral mass.
Visceral mass
Coelom
Mantle
Mantle
cavity
Intestine
Gonads
Stomach
Shell
Radula
Anus
The nervous
system consists
of a nerve ring
around the
esophagus, from
which nerve
cords extend.
Gill
Foot
Nerve
cords
Esophagus
Mouth
Mouth
Radula. The mouth
region in many
mollusc species
contains a rasp-like
feeding organ
called a radula. This
belt of backwardcurved teeth slides
back and forth,
scraping and
scooping like a
backhoe.
Classes of molluscs
Chitons

Class Polyplacophora is composed of the
chitons (Oval-shaped marine animals encased
in an armor of eight dorsal plates)
Gastropods

About three-quarters of all
living species of molluscs
belong to class Gastropoda
(a) A land snail
(b) A sea slug. Nudibranchs, or sea slugs, lost their shell
during their evolution.
Gastropods

Gastropod characteristics




Most are marine, but there are also
many freshwater and terrestrial
species
Possess a single, spiraled shell
Slugs lack a shell or have a
reduced shell
The most distinctive characteristic
of this class is a developmental
process known as torsion, which
causes the animal’s anus and
mantle to end up above its head
Mantle
cavity
Anus
Mouth
Stomach
Intestine
Bivalves (Molluscs of class Bivalvia)
 Include
many species of clams, oysters,
mussels, and scallops
 Have a shell divided into two halves
Bivalves

The mantle cavity of a bivalve contains gills that
are used for feeding as well as gas exchange
Hinge area
Mantle
Gut
Coelom
Heart
Shell
Adductor
muscle
Mouth
Anus
Excurrent
siphon
Palp
Water
flow
Foot
Mantle
cavity
Gill
Incurrent
siphon
Clam locomotion
Cephalopods

Class Cephalopoda includes squids and
octopuses
 Carnivores
with beak-like jaws surrounded by
tentacles of their modified foot
Octopus

Most octopuses creep along the sea floor in
search of prey
(a) Octopuses are considered among the
most intelligent invertebrates.
Squid

Squids use their siphon to fire a jet of water,
which allows them to swim very quickly
(b) Squids are speedy carnivores with
beaklike jaws and well-developed eyes.
`One small group of shelled cephalopods

 The
nautiluses, survives today
(c) Chambered nautiluses are the only living
cephalopods with an external shell.
Annelids

Annelids
 Segmented
worms
 Have bodies composed of a series of fused
rings
 3 Classes Oligochaeta, Polychaeta, Hirudinea
Classes of Annelida
Oligochaetes

Oligochaetes (class Oligochaeta)



Are named for their relatively sparse chaetae (bristles made of
chitin)
Include the earthworms and a variety of aquatic species
Earthworms eat their way through the soil, extracting
nutrients as the soil moves through the alimentary canal

Which helps till the earth, making earthworms valuable to
farmers
Earthworm anatomy
Coelom. The coelom
of the earthworm is
partitioned by septa.
Each segment is surrounded by longitudinal muscle, which in
turn is surrounded by circular muscle. Earthworms coordinate
the contraction of these two sets of muscles to move (see
Figure 49.25). These muscles work against the noncompressible
coelomic fluid, which acts as a hydrostatic skeleton.
Epidermis
Septum
(partition
between
segments)
Circular
muscle
Many of the internal
structures are repeated
within each segment of
the earthworm.
Chaetae. Each segment
has four pairs of
chaetae, bristles that
provide traction for
burrowing.
Longitudinal
muscle
Dorsal
vessel
Anus
Intestine
Nerve
cords
Cerebral ganglia. The
earthworm nervous system
features a brain-like pair of
cerebral ganglia above and
in front of the pharynx. A ring
of nerves around the pharynx
connects to a subpharyngeal
ganglion, from which a fused
pair of nerve cords runs
posteriorly.
Cuticle
Metanephridium. Each
segment of the worm
contains a pair of
excretory tubes, called
metanephridia, with
ciliated funnels, called
nephrostomes. The
metanephridia remove
wastes from the blood
and coelomic fluid
through exterior pores.
Nephrostome
Pharynx
Tiny blood vessels are
abundant in the earthworm’s
skin, which functions as its
respiratory organ. The blood
contains oxygen-carrying
hemoglobin.
Ventral
vessel
Clitellum
Esophagus
Metanephridium
Crop
Giant Australian earthworm
Intestine
Gizzard
Mouth
Subpharyngeal
ganglion
The circulatory system, a network of vessels,
is closed. The dorsal and ventral vessels are linked
by segmental pairs of vessels. The dorsal vessel
and five pairs of vessels that circle the esophagus
of an earthworm are muscular and pump blood
through the circulatory system.
Ventral nerve cords with segmental ganglia.
The nerve cords penetrate the septa and run
the length of the animal, as do the digestive
tract and longitudinal blood vessels.
Polychaetes

Members of class Polychaeta possess
paddlelike parapodia that function as gills and
aid in locomotion
Parapodia
Leeches

Members of class
Hirudinea are
blood-sucking
parasites, such as
leeches
Nematodes (roundworms)


Nematodes are nonsegmented
pseudocoelomates covered by
a tough cuticle
Among the most widespread of
all animals, nematodes, or
roundworms
 Are
found in most aquatic
habitats, in the soil, in moist
tissues of plants, and in the body
fluids and tissues of animals
Nematode movie
Nematodes

The cylindrical bodies of nematodes are
covered by a tough coat called a cuticle
25 µm
Nematodes

Some species of nematodes are important
parasites of plants and animals
Encysted juveniles
Trichinella
spiralis
encysted in
human
muscle
tissue
Muscle tissue
50 µm
Arthropods
Arthropods are segmented coelomates that
have an exoskeleton and jointed
appendages
 Two out of every three known species of
animals are arthropods
 Members of the phylum Arthropoda

 Are
found in nearly all habitats of the biosphere
Arthropod Characteristics

The diversity and success of arthropods
 Are
largely related to their segmentation, hard
exoskeleton, and jointed appendages

Arthropods have an open circulatory system
 In
which fluid called hemolymph is circulated into the
spaces surrounding the tissues and organs



A variety of organs specialized for gas exchange
have evolved in arthropods
The body of an arthropod is completely covered
by the cuticle, an exoskeleton made of chitin
When an arthropod grows it molts its
exoskeleton in a process called ecdysis
Segmentation



Early arthropods, such as trilobites
showed little variation from segment to
segment
As arthropods evolved the segments
fused, and the appendages became more
specialized
The appendages of some living
arthropods are modified for many different
functions
Cephalothorax Abdomen
Antennae
(sensory
reception)
Head Thorax
Swimming
appendages
Walking legs
Pincer (defense) Mouthparts (feeding)
Subphyla of Arthropoda
Cheliceriforms

Named for clawlike
feeding appendages
called chelicerae
 Includes
spiders, ticks,
mites, scorpions, and
horseshoe crabs

Most of the marine
cheliceriforms are
extinct
 But
some species
survive today,
including the
horseshoe crabs
Cheliceriforms

Most modern cheliceriforms are
arachnids
 A group that includes spiders,
scorpions, ticks, and mites
50 µm
(a) Scorpions have pedipalps that are pincers (b) Dust mites are ubiquitous scavengers in (c) Web-building spiders are generally
specialized for defense and the capture of
human dwellings but are harmless except
most active during the daytime.
food. The tip of the tail bears a poisonous
to those people who are allergic to them
stinger.
(colorized SEM).
Arachnids

Arachnids have an abdomen and a cephalothorax

Which has six pairs of appendages, the most anterior of which
are the chelicerae. (4 pairs of walking legs)
Intestine
Digestive
gland
Stomach
Heart
Brain
Eyes
Poison
gland
Ovary
Anus
Book lung
Spinnerets
Silk gland
Sperm
Gonopore
(exit for eggs) receptacle
Chelicera
Pedipalp
Myriapods

Subphylum Myriapoda


Millipedes, class Diplopoda



Includes millipedes and
centipedes
Have a large number of legs
Each trunk segment has two
pairs of legs
Centipedes, class
Chilopoda


Are carnivores with jaw-like
mandibles
Have one pair of legs per
trunk segment
Insects

Subphylum Hexapoda, insects and their
relatives
 Are
more species-rich than all other forms of
life combined
 Live in almost every terrestrial habitat and in
fresh water
 The internal anatomy of an insect includes
several complex organ systems
Insect anatomy
The insect body has three regions: head,
thorax, and abdomen. The segmentation
of the thorax and abdomen are obvious,
but the segments that form the head are fused.
Abdomen
Thorax
Head
Compound eye
Heart. The
insect heart
drives hemolymph
through an
open circulatory
system.
Cerebral ganglion. The two nerve
cords meet in the head, where the
ganglia of several anterior segments
are fused into a cerebral ganglion
(brain). The antennae, eyes, and
other sense organs are concentrated
on the head.
Antennae
Ovary
Malpighian tubules.
Anus
Metabolic wastes are
removed from the
Vagina
hemolymph by excretory
organs called Malpighian
tubules, which are outpocketings of the
digestive tract.
Tracheal tubes. Gas exchange in insects is
accomplished by a tracheal system of branched,
chitin-lined tubes that infiltrate the body and
carry oxygen directly to cells. The tracheal
system opens to the outside of the body
through spiracles, pores that can control air
flow and water loss by opening or closing.
Nerve cords. The insect
nervous system
consists of a pair of
ventral nerve cords
with several
segmental ganglia.
Dorsal
artery
Crop
Insect mouthparts are formed from
several pairs of modified appendages.
The mouthparts include mandibles,
which grasshoppers use for chewing.
In other insects, mouthparts are
specialized for lapping, piercing, or
sucking.
Insects

Flight is one key to the great success of
insects
 An
animal that can fly can escape predators,
find food, and disperse to new habitats much
faster than organisms that can only crawl
Metamorphosis


Many insects undergo metamorphosis during their
development
In incomplete metamorphosis, the young, called
nymphs




Resemble adults but are smaller and go through a series of molts
until they reach full size (example: grasshoppers)
Insects with complete metamorphosis have larval stages
specialized for eating and growing that are known by such
names as maggot, grub, or caterpillar
The larval stage looks entirely different from the adult stage
Metamorphosis from the larval stage to the adult stage
occurs during a pupal stage
Metamorphosis
movie
(a) Larva (caterpillar)
(b) Pupa
(c) Pupa
(d) Emerging adult
(e) Adult
26 Orders of Insects
ORDER
Blattodea
Coleoptera
Dermaptera
Diptera
Hemiptera
Hymenoptera
Isoptera
APPROXIMATE
NUMBER OF
SPECIES
4,000
350,000
1,200
151,000
85,000
125,000
2,000
MAIN CHARACTERISTICS
EXAMPLES
Cockroaches have a dorsoventrally flattened body, with legs
modified for rapid running. Forewings, when present, are
leathery, whereas hind wings are fanlike. Fewer than 40 cockroach species live in houses; the rest exploit habitats ranging
from tropical forest floors to caves and deserts.
German
cockroach
Beetles comprise the most species-rich order of insects. They
have two pairs of wings, one of which is thick and leathery, the
other membranous. They have an armored exoskeleton and
mouthparts adapted for biting and chewing. Beetles undergo
complete metamorphosis.
Japanese
beetle
Earwigs are generally nocturnal scavengers. While some
species are wingless, others have two pairs of wings, one of
which is thick and leathery, the other membranous. Earwigs
have biting mouthparts and large posterior pincers. They undergo incomplete metamorphosis.
Dipterans have one pair of wings; the second pair has become
modified into balancing organs called halteres. Their head is
large and mobile; their mouthparts are adapted for sucking,
piercing, or lapping. Dipterans undergo complete metamorphosis. Flies and mosquitoes are among the best-known dipterans,
which live as scavengers, predators, and parasites.
Hemipterans are so-called “true bugs,” including bed bugs,
assassin bugs, and chinch bugs. (Insects in other orders are
sometimes erroneously called bugs.) Hemipterans have two
pairs of wings, one pair partly leathery, the other membranous.
They have piercing or sucking mouthparts and undergo
incomplete metamorphosis.
Ants, bees, and wasps are generally highly social insects. They
have two pairs of membranous wings, a mobile head, and
chewing or sucking mouthparts. The females of many species
have a posterior stinging organ. Hymenopterans undergo complete metamorphosis.
Termites are widespread social insects that produce enormous
colonies. It has been estimated that there are 700 kg of
termites for every person on Earth! Some termites have two
pairs of membranous wings, while others are wingless. They
feed on wood with the aid of microbial symbionts carried in
specialized chambers in their hindgut.
Earwig
Horsefly
LeafFooted
bug
Cicada-killer wasp
Termite
26 Orders of Insects
ORDER
Lepidoptera
Odonata
APPROXIMATE
NUMBER OF
SPECIES
120,000
5,000
EXAMPLE
MAIN CHARACTERISTICS
Butterflies and moths are among the best-known insects. They
have two pairs of wings covered with tiny scales. To feed, they
uncoil a long proboscis. Most feed on nectar, but some species
feed on other substances, including animal blood or tears.
Swallowtail
butterfly
Dragonflies and damselflies have two pairs of large, membranous wings. They have an elongated abdomen, large, compound
eyes, and chewing mouthparts. They undergo incomplete metamorphosis and are active predators.
Dragonfly
Orthoptera
13,000
Grasshoppers, crickets, and their relatives are mostly herbivorous. They have large hind legs adapted for jumping, two
pairs of wings (one leathery, one membranous), and biting or
chewing mouthparts. Males commonly make courtship sounds
by rubbing together body parts, such as a ridge on their hind
leg. Orthopterans undergo incomplete metamorphosis.
Katydid
Phasmida
Phthiraptera
Siphonaptera
Thysanura
2,600
2,400
2,400
450
Stick insects and leaf insects are exquisite mimics of plants. The
eggs of some species even mimic seeds of the plants on which the
Insects live. Their body is cylindrical or flattened dorsoventrally.
They lack forewings but have fanlike hind wings. Their
mouthparts are adapted for biting or chewing.
Commonly called sucking lice, these insects spend their entire
life as an ectoparasite feeding on the hair or feathers of a single
host. Their legs, equipped with clawlike tarsi, are adapted for
clinging to their hosts. They lack wings and have reduced eyes.
Sucking lice undergo incomplete metamorphosis.
Fleas are bloodsucking ectoparasites on birds and mammals.
Their body is wingless and laterally compressed. Their legs are
modified for clinging to their hosts and for long-distance
jumping. They undergo complete metamorphosis.
Stick insect
Human
Body
louse
Flea
Silverfish are small, wingless insects with a flattened body and
reduced eyes. They live in leaf litter or under bark. They can also
infest buildings, where they can become pests.
Silverfish
Trichoptera
7,100
The larvae of caddisflies live in streams, where they make houses
from sand grains, wood fragments, or other material held together by silk. Adults have two pairs of hairy wings and chewing
or lapping mouthparts. They undergo complete metamorphosis.
Caddisfly
Crustaceans

While arachnids and insects thrive on land


Crustaceans, for the most part, have remained in marine and
freshwater environments
Crustaceans, subphylum Crustacea

Typically have biramous (branched) appendages that are
extensively specialized for feeding and locomotion
Decapods

Decapods are all relatively large crustaceans
 And include lobsters, crabs, crayfish, and shrimp
Ghost crabs (genus Ocypode) live on sandy ocean
beaches worldwide. Primarily nocturnal, they take
shelter in burrows during the day.
Decapod movie
Planktonic crustaceans

Planktonic crustaceans include
many species of copepods
 Which are among the most
numerous of all animals
Planktonic crustaceans
known as krill are
consumed in vast
quantities by whales.
Barnacles

Barnacles are a group of mostly sessile crustaceans
whose cuticle is hardened into a shell
The jointed appendages
projecting from the shells
of these barnacles capture
organisms and organic
particles suspended in
the water.
Deuterostomes
Echinoderms and chordates are
deuterostomes
 Chordates and echinoderms share the
characteristics of deuterostomes

 Radial
cleavage
 Formation of the mouth at the end of the
embryo opposite the blastopore
Echinoderms

Echinoderm characteristics
 Sea
stars and most other echinoderms are slowmoving or sessile marine animals
 A thin, bumpy or spiny skin covers an endoskeleton of
hard calcareous plates
 Unique to echinoderms is a water vascular system
network of hydraulic canals branching into tube feet that
function in locomotion, feeding, and gas exchange
Echinoderm movie
Echinoderm anatomy
A short digestive tract runs from the
mouth on the bottom of the central
disk to the anus on top of the disk.
Central disk. The central
disk has a nerve ring and
nerve cords radiating from
the ring into the arms.
Digestive glands secrete
digestive juices and aid in
the absorption and storage
of nutrients.
Radial canal. The water vascular
system consists of a ring canal in the
central disk and five radial canals,
each running in a groove down the
entire length of an arm.
Stomach
Anus
Spine
Gills
Ring
canal
Gonads
Radial
nerve
The surface of a sea star is
covered by spines that help
defend against predators, as
well as by small gills that
provide gas exchange.
Madreporite. Water can flow
in or out of the water vascular
system into the surrounding
water through the madreporite.
Ampulla
Podium
Tube
feet
Branching from each radial canal are hundreds of hollow, muscular tube
feet filled with fluid. Each tube foot consists of a bulb-like ampulla and
suckered podium (foot portion). When the ampulla squeezes, it forces
water into the podium and makes it expand. The podium then
contacts the substrate. When the muscles in the wall of the podium
contract, they force water back into the ampulla, making the podium
shorten and bend.
Echinoderm classes
Sea Stars

Sea stars, class Asteroidea
 Have
multiple arms radiating from a central disk
 The undersurfaces of the arms bear tube feet,
each of which can act like a suction disk
(a) A sea star (class Asteroidea)
Brittle Stars

Brittle stars have a distinct central disk and
long, flexible arms
(b) A brittle star (class Ophiuroidea)
Sea Urchins and Sand Dollars

Sea urchins and sand dollars have no
arms, but they do have five rows of tube
feet that function in movement
Sand Dollar
Sea Urchin
Sea Lilies and Feather Stars


Sea lilies live attached to the substrate by a stalk
Feather stars
 Crawl
about using their long, flexible arms
(d) A feather star (class Crinoidea)
Sea Cucumbers

Sea cucumbers do not look much like
other echinoderms
 They
lack spines, and their endoskeleton is
much reduced
(e) A sea cucumber (class Holothuroidea)
Sea Daisies

Sea daisies were discovered in 1986
 And
only two species are known
(f) A sea daisy (class Concentricycloidea)
Chordates (Phylum Chordata)

Chordates
 Two
subphyla of invertebrates as well as the
hagfishes and the vertebrates
 Share many features of embryonic development
with echinoderms
Review of Animal Phyla