Transcript Invertebrate taxa to know for BIO 111 2007

Chapter 33: Invertebrates
33 of the 34 phyla of animals are invertebrates
Eumetazoa
Ancestral colonial
choanoflagellate
Chordata
Echinodermata
Other bilaterians (including
Nematoda, Arthropoda,
Mollusca, and Annelida)
Cnidaria
Porifera
Figure 33.2 Review of animal phylogeny
Deuterostomia
Bilateria
Invertebrate taxa to know for BIO 111 2007
Total # of phyla:
# presented in textbook:
# discussed here:
(# classes you need to know:
34
24
9
24)
Invertebrate taxa to know for BIO 111 2007
Porifera – sponges
Arthropoda
Cnidaria
Hexapoda - insects
Hydrozoa - Hydra
Crustacea – crabs. shrimp, barnacles
Scyphozoa - jellyfish
Myriapods – centipedes, millipedes
Cubozoa – sea wasps
Cheliceriforms – spiders, mites, ticks
Anthozoa – sea anemones & corals
Platyhelminthes – flatworms
Echinodermata
Turbellaria
Asteroidea – sea stars
Trematoda
Opiuroidea – brittle stars
Cestoda
Echinoidea – sea urchins, sand $’s
Nematoda
Crinoidea – sea lilies
Rotifera
Holothuroidea – sea cucumbers
Mollusca
Concentricycloidea – sea daisies
Polyplacophora – chitons
Gastropoda – snails
Bivalvia – clams & mussels
Cephalopodia – squids & octopi
Annelida
Polychaeta – more worms
Oligochaeta – earthworms
Hirudinea - leeches
Phylum Porifera - sponges
Adam Laverty
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)
Flagellum
Food particles
Collar in mucus
Choanocyte
Osculum
4 Spongocoel. Water
passing through porocytes
enters a cavity called the
spongocoel.
Phagocytosis of
food particles
3 Porocytes. Water enters
6
the epidermis through
channels formed by
porocytes, doughnut-shaped
cells that span the body wall.
Spicules
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”).
Amoebocyte
Water
flow
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).
Phylum Cnidaria
Phylum Cnidaria (basal metazoan)
Polyp
Medusa
Mouth/anus
Tentacle
Gastrovascular
cavity
Gastrodermis
Mesoglea
Body
stalk
Epidermis
Tentacle
Mouth/anus
A cnidocyte with a nematocyst
Prey
Tentacle
“Trigger”
Nematocyst
Discharge
Of thread
Coiled thread
Cnidocyte
Cnidarians
(a) These colonial polyps are members of
class Hydrozoa.
(b) Many species of jellies (class
Scyphozoa), including the
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.
33.7 Jelly Swimming
corals of Class Anthozoa
Phylum Platyhelminthes
A Turbellarian
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.
Schistosomiasis (bilharzia) is caused by a
trematode
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
Class Cestoda: tapeworms
red meat
fish
Proglottids with
reproductive structures
200 µm
Scolex
Hooks
Sucker
Phylum Rotifera
0.1 mm
Lophophorates (several phyla)
Lophophore
Lophophore
Lophophore
(a) Ectoprocts, such as this sea (b) In phoronids such as
mat (Membranipora
Phoronis hippocrepia, the
membranacea), are colonial
lophophore and mouth
lophophorates.
are at one end of an
elongated trunk.
(c) Brachiopods have a hinged shell.
The two parts of the shell are
dorsal and ventral.
A ribbon worm, phylum Nemertea, is a
lophophorate
Phylum Mollusca
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
The nervous
system consists
of a nerve ring
around the
esophagus, from
which nerve
cords extend.
Intestine
Gonads
Stomach
Shell
Radula
Anus
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.
A chiton, class Polyplacophora
Class Gastropoda
(limpets, too)
(a) A land snail
(b) A sea slug. Nudibranchs, or sea slugs, lost their shell
during their evolution.
The results of torsion in a gastropod
Stomach
Mantle
cavity
Anus
Mouth
Intestine
Class Bivalvia
Figure 33.21 Anatomy of a clam
Hinge area
Mantle
Gut
Coelom
pearls
Heart
Shell
Adductor
muscle
Mouth
Anus
Excurrent
siphon
Palp
Water
flow
Foot
Mantle
cavity
Gill
Incurrent
siphon
glochidia of a bivalve
Class Cephalopoda
(b) Squids are speedy carnivores
with beaklike jaws and welldeveloped eyes.
(a) Octopuses are considered among the
most intelligent invertebrates.
“head-foot”
shell is internal (beak)
reproduction
camouflage & ink
brains
(c) Chambered nautiluses are the only living
cephalopods with an external shell.
show the movies
Phylum Annelida – the segmented worms
Chaetae. Each segment
has four pairs of
chaetae, bristles that
provide traction for
burrowing.
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.
Epidermis
Cuticle
Circular
muscle
Many of the internal
structures are repeated
within each segment of
the earthworm.
Metanephridium. Each
segment of the worm
contains a pair of
excretory tubes, called
metanephridia, with
ciliated funnels, called
Septum
nephrostomes. The
(partition
metanephridia remove
between
wastes from the blood
segments) and coelomic fluid
through exterior pores.
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.
Longitudinal
muscle
Dorsal
vessel
Anus
Intestine
Nerve
cords
Tiny blood vessels are
abundant in the earthworm’s
skin, which functions as its
respiratory organ. The blood
contains oxygen-carrying
hemoglobin.
Ventral
vessel
Nephrostome Clitellum
Pharynx Esophagus
Metanephridium
Crop
Giant Australian earthworm
Intestine
Gizzard
Mouth
Subpharyngeal
ganglion
Ventral nerve cords with segmental ganglia.
The circulatory system, a network of vessels,
The nerve cords penetrate the septa and run
is closed. The dorsal and ventral vessels are
the length of the animal, as do the digestive
linked by segmental pairs of vessels. The dorsal
tract and longitudinal blood vessels.
vessel and five pairs of vessels that circle the esophagus
of an earthworm are muscular and pump blood through
the circulatory system.
Darwin again: “1 acre of British farmland contained
about 50,000 earthworms that produced 18 tons of
castings per year” (Campbell & Reese)
Invasive species?
A polychaete Annelid
Parapodia
A leech, class Hirudinea
mostly freshwater, but watch out for
those terrestrial forms.
predators, parasites, scavengers
reduced anatomy
Some parasites highly specialized
hirudin
anaesthesia
vasodilators
HOWARD LIPIN / Union-Tribune
Phylum Nematoda
25 µm
Trichinosis is caused by parasitic nematodes
Encysted juveniles
Muscle tissue
50 µm
Trilobites were early arthropods, >250 mya
Cephalothorax
Antennae
(sensory
reception)
Head
Abdomen
Thorax
Swimming
appendages
Walking legs
Pincer (defense)
Mouthparts (feeding)
Horseshoe crabs are Cheliceriforms
Arachnids are cheliceriforms
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).
Intestine
Digestive
gland
Stomach
Brain
Heart
Eyes
Poison
gland
Ovary
Anus
Book lung
Spinnerets
Silk gland
Gonopore
(exit for eggs)
Sperm
receptacle
Chelicera
Pedipalp
millipedes are myriapods
Centipedes are myriapods
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
Cerebral ganglion. The two nerve
Heart. The
cords meet in the head, where the
insect heart
ganglia of several anterior segments
drives hemolymph are fused into a cerebral ganglion
through an
(brain). The antennae, eyes, and
open circulatory
other sense organs are concentrated
system.
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.
Metamorphosis (ecydsis)
(a) Larva (caterpillar)
(b) Pupa
(c) Pupa
(d) Emerging adult
(e) Adult
ORDER
Blattodea
Coleoptera
Dermaptera
Diptera
Hemiptera
Hymenoptera
APROXIMATE
NUMBER OF
SPECIES
4,000
350,000
1,200
151,000
85,000
125,000
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.
Earwig
Horsefly
LeafFooted
bug
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.
Cicada-killer wasp
Isoptera
2,000
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.
Termite
ORDER
Lepidoptera
Odonata
APROXIMATE
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
2,600
2,400
2,400
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.
Stick insect
Human
Body
louse
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.
Flea
Thysanura
450
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
Class Crustacea
(a) Ghost crabs (genus Ocypode) live on sandy ocean
beaches worldwide. Primarily nocturnal, they take
shelter in burrows during the day.
(b) Planktonic crustaceans
known as krill are
consumed in vast
quantities by whales.
(c) The jointed appendages
projecting from the shells
of these barnacles capture
organisms and organic
particles suspended in
the water.
Phylum Echinodermata
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.
Spine
Stomach
Anus
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.
Gills
Madreporite. Water can flow
in or out of the water vascular
system into the surrounding
water through the madreporite.
Digestive glands secrete
digestive juices and aid in
the absorption and storage
of nutrients.
Ring
canal
Gonads
Radial
nerve
Ampulla
Podium
Tube
feet
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.
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.
(a) A sea star (class Asteroidea)
(b) A brittle star (class Ophiuroidea)
(c) A sea urchin (class Echinoidea)
(d) A feather star (class Crinoidea)
(e) A sea cucumber (class Holothuroidea)
(f) A sea daisy (class Concentricycloidea)