chapter 33

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

PowerPoint® Lecture Presentations for

Biology Eighth Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp

Chapter 33Chapter 33

Invertebrates

Fig. 33-1


Overview: Life Without a Backbone

• Invertebrates are animals that lack a backbone

• They account for 95% of known animal species

Fig. 33-2

ANCESTRALPROTIST

Commonancestor ofall animals

Calcareaand Silicea

Eu

me

tazo

a

Bila

teria

Cnidaria

Mollusca/Annelida

Nematoda/Arthropoda

Chordata/Echinodermata

Sponges/“Porifera”

Fig. 33-3a

A sponge A jelly

Phylum Choanocytes Phylum Cnidaria(“Porifera”)

Fig. 33-3a

Phylum Platyhelminthes Phylum Rotifera

A marine flatworm A rotifer (LM)

Fig. 33-3m

An octopus

Phylum Mollusca Phylum Annelida

A marine annelid

Fig. 33-3s

A roundworm A scorpion(an arachnid)

Phylum Nematoda Phylum Arthropoda

Fig. 33-3v

A sea urchin

Phylum Echinodermata Phylum Chordata

A tunicate


Concept 33.1: Sponges are basal animals that lack true tissues

• Sponges are sedentary, filter feeding animals from the phyla Calcarea and Silicea “Porifera”

• They live in both fresh and marine waters

• Sponges lack true tissues and organs

• Possess collar cells to propel water through the body and strain food particles.

• Food digested intracellularly by amebocytes

• Most asymmetrical

• http://www.youtube.com/watch?v=RmPTM965-1c&feature=related (sponge feeding)

Fig. 33-4

Azure vase sponge (Callyspongiaplicifera)

Spongocoel

Osculum

Pore

Epidermis Waterflow

Mesohyl

Choanocyte

Flagellum

Collar

Food particlesin mucus

Choanocyte

AmoebocytePhagocytosis offood particles

Spicules

Amoebocytes


Concept 33.2: Cnidarians are an ancient phylum of eumetazoans

• All animals except sponges and a few other groups are animals with true tissues (Eumetazoa)

• Phylum Cnidaria: jellies, corals, sea anemones

• Radial symmetrical carnivores

• Diplobastic - Two body layers: ectoderm & endoderm

• Possess gastrovascular cavity (not a complete tube) and nematocysts

• There are two variations on the body plan: the sessile polyp and motile medusa

Fig. 33-5

PolypMouth/anus

Bodystalk

Tentacle

Gastrovascularcavity

Gastrodermis

Mesoglea

Epidermis

TentacleMouth/anus

Medusa

Fig. 33-6

Tentacle

Nematocyst

“Trigger”

Cuticleof prey

Threaddischarges

Thread(coiled)

Cnidocyte

Thread

Fig. 33-7

(a) Colonial polyps (class Hydrozoa)

(b) Jellies (class Scyphozoa)

Sea wasp (classCubozoa)

(d) Sea anemone (class Anthozoa)

(c)


Conceptual Summary

• Sponges and cnidarians are almost entirely marine and are considered primitive because they do not possess three body layers nor true organs

• http://www.youtube.com/watch?v=zkF_1r6ll54&feature=related (hydra eating)

• http://www.youtube.com/watch?v=a5oHMjGqjyo (budding in hydra)

Fig. 33-8-1

Feedingpolyp

Reproductivepolyp

Medusabud

Medusa

ASEXUALREPRODUCTION(BUDDING)Portion of

a colonyof polyps

1 m

m

Key

Haploid (n)Diploid (2n)

Fig. 33-8-2

Feedingpolyp

Reproductivepolyp

Medusabud

Medusa


a colonyof polyps

1 m

m

Key


Gonad

SEXUALREPRODUCTION

MEIOSIS

FERTILIZATION

Egg Sperm

Zygote

Fig. 33-8-3

Feedingpolyp

Reproductivepolyp

Medusabud

Medusa


a colonyof polyps

1 m

m

Key


Gonad

SEXUALREPRODUCTION

MEIOSIS

FERTILIZATION

Egg Sperm

Zygote

Planula(larva)

Developingpolyp

Maturepolyp

Medusa producedby asexual budding


Platyhelminthes: Flatworms

• Acoelomates – solid body, without a body cavity

• Bilateral symmetry and beginnings of cephalization

• Development of true organs, tripbloblastic (three body layers); ectoderm, endoderm, mesoderm

• No coelom (body cavity)

• Digestibe tract incomplete – only one opening that braches throughout the body to distribute food

• http://www.youtube.com/watch?v=5fx-YgcP8Gg (flatworm mating behavior – Rated R)

Fig. 33-9

Fig. 33-10

Pharynx

Gastrovascularcavity

Mouth

Eyespots

Ganglia Ventral nerve cords

Fig. 33-12

Proglottids withreproductive structures

Hooks

Sucker

Scolex

200 µm

• Tapeworms are parasites of vertebrates and lack a digestive system• Tapeworms absorb nutrients from the host’s intestine• Fertilized eggs, produced by sexual reproduction, leave the host’s

body in feces


Rotifera

• Pseudocoelomates – body cavity between digestibe tract and body wall is not completely lined by mesoderm

• Rotifers have an alimentary canal, a digestive tube with a separate mouth and anus (complete digestive tract) that lies within a fluid-filled pseudocoelom

• http://www.youtube.com/watch?v=PALgTXQOqQo&feature=related (rotifer feeding)

Fig. 33-13

Jaws Crownof cilia

AnusStomach 0.1 mm


Nematoda: Roundworms

• Nematodes, or roundworms, are found in most aquatic habitats, in the soil, in moist tissues of plants, and in body fluids and tissues of animals

• Pseudocoelomates

• They have an alimentary canal, but lack a circulatory system

• Reproduction in nematodes is usually sexual, by internal fertilization

• http://video.google.com/videoplay?docid=-2019570087567872766# (C. elegans crawling)

Fig. 33-25

25 µm


Conceptual Summary

• Flatworms and roundworms have bilateral symmetry, the beginnings of cephalization, and three body layers with well developed tissues and organs. Phyla include many important parasites of humans.


• All of the animals that we cover from this point on are coelomates – body cavity (coelom) is completely lined by mesoderm. Groups are divided as protostomes or deuterostomes


Mollusca

• Phylum Mollusca includes snails and slugs, oysters and clams, and octopuses and squids

• Basic body plan of muscular head-food, with body on top a loosely covered mantle which may secrete a shell

• Gastropods have a well defined head, tentacles and elongated flattened foot

• Marine and freshwater filter feeders have a body flattened between two valves of a hinged she. Bivalvia

• Cephalopods are on the the most advanced invertebrate groups (octopus, squid, nautilus)

• Protostomes

Fig. 33-15

Nephridium Visceral mass

Coelom

Mantle

Mantlecavity

Heart

Intestine

Gonads

Stomach

Shell

Radula

MouthEsophagusNerve

cordsFoot

Gill

Anus

Mouth

Radula

Fig. 33-16

Fig. 33-17

(a) A land snail

(b) A sea slug

Fig. 33-19

Fig. 33-20

Mouth

Digestivegland

MantleHinge area

Gut

Coelom

Heart Adductormuscle

Anus

Excurrentsiphon

Waterflow

IncurrentsiphonGillGonad

Mantlecavity

Foot

Palp

Shell

Fig. 33-21

Octopus

Squid

Chambered nautilus

http://www.youtube.com/watch?v=OBg0k9GbHiw&feature=fvwrel (squid inking)

http://www.youtube.com/watch?v=QMFqV4SJLWg (nautilus)


Annelida: Segmented Worms

• Possess a coelom and closed circulatory system

• Body segmented - septa

• Protostomes

Fig. 33-22

Epidermis

Circularmuscle

Longitudinalmuscle

Dorsal vessel

Chaetae

Intestine

Nephrostome

Fusednervecords

Ventralvessel

Metanephridium

Septum(partitionbetweensegments)

CoelomCuticle

Anus

Metanephridium

Crop

Intestine

Gizzard

Ventral nerve cord withsegmental gangliaBlood

vessels

Subpharyngealganglion

MouthCerebral ganglia

Pharynx

Esophagus

Clitellum

Giant Australian earthworm

Fig. 33-23

Parapodia

Fig. 33-24


Arthropoda: (jointed foot)

• Major evolutionary advances over other invertebrate groups include exoskeleton (chitin) and jointed appendages

• Open circulatory system in which fluid called hemolymph is circulated into the spaces surrounding the tissues and organs (fig. 42.3 pg. 900)

• Main groups are arachnids (spiders, ticks), crustaceans (lobsters, crabs, shrimp, krill), and insects

• Rotostomes

Fig. 33-29

Cephalothorax

Antennae(sensoryreception) Head

Thorax

Abdomen

Swimming appendages(one pair locatedunder eachabdominal segment)

Walking legs

Mouthparts (feeding)Pincer (defense)

Fig. 33-30

Fig. 33-31

Scorpion

Dust mite

Web-building spider

50 µm


• Arachnids have an abdomen and a cephalothorax, which has six pairs of appendages, the most anterior of which are the chelicerae

• Gas exchange in spiders occurs in respiratory organs called book lungs

• Many spiders produce silk, a liquid protein, from specialized abdominal glands

Fig. 33-32

Intestine

HeartDigestivegland

Ovary

Anus

Spinnerets

Silk gland

Gonopore(exit for eggs) Sperm

receptacle

Book lung

Chelicera Pedipalp

Poisongland

Eyes

Brain

Stomach

Fig. 33-33

Fig. 33-34

Fig. 33-35

Abdomen Thorax Head

Compound eye

Antennae

Heart

Dorsalartery Crop

Cerebral ganglion

Mouthparts

Nerve cords

Tracheal tubesOvary

Malpighiantubules

Vagina

Anus


• 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

• 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

• Insects with complete metamorphosis have larval stages known by such names as maggot, grub, or caterpillar

• The larval stage looks entirely different from the adult stage

• http://www.youtube.com/watch?v=NnJA_BkPF_Y (butterfly metamorphosis)

Fig. 33-36

(a) Larva (caterpillar)(b) Pupa

(c) Later-stage pupa (d) Emerging

adult

(e) Adult


• Most insects have separate males and females and reproduce sexually

• Individuals find and recognize members of their own species by bright colors, sound, or odors

• Some insects are beneficial as pollinators, while others are harmful as carriers of diseases, or pests of crops


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 branched appendages that are extensively specialized for feeding and locomotion

• Most crustaceans have separate males and females

Fig. 33-38

(a) Ghost crab

(b) Krill (c) Barnacles


Conceptual Summary

• The chitinous exoskeleton of arthropods, with its many jointed appendages modified for a variety of jobs, proved so versatile that the arthropods have undergone impressive adaptive radiation with more species and individuals than any other phylum


Concept 33.5: Echinoderms and chordates are deuterostomes

• Sea stars and other echinoderms, phylum Echinodermata, may seem to have little in common with phylum Chordata, which includes the vertebrates

• Shared characteristics define deuterostomes (Chordates and Echinoderms)

– Radial cleavage

– Formation of the mouth at the end of the embryo opposite the blastopore


Echinodermata: Sea urchins, sea stars and sea cucumbers

• Sea stars and most other echinoderms are slow-moving or sessile marine animals

• Deuterostomes

• Vertebrates are more closely related to echinoderms than to annelids, mollusks or arthropods based on studies of embryonic development

• Echinoderms have a unique water vascular system, a network of hydraulic canals branching into tube feet that function in locomotion, feeding, and gas exchange

• Possess a skeleton of calcium carbonate just under the skin

• Immature have bilateral symmetry, however, most adults have pentaradial symmetry

• http://www.youtube.com/watch?v=A100m5EpfFI&feature=related (sea star feeding)

Fig. 33-39

AnusStomach

Spine

Gills

Madreporite

Radialnerve

Gonads

Ampulla

Podium

Tubefeet

Radial canal

Ringcanal

Central disk

Digestive glands

Fig. 33-40a

(a) A sea star (class Asteroidea)

Fig. 33-40b

(b) A brittle star (class Ophiuroidea)

Fig. 33-40c

(c) A sea urchin (class Echinoidea)

Fig. 33-40d

(d) A feather star (class Crinoidea)

Fig. 33-40e

(e) A sea cucumber (class Holothuroidea)

Fig. 33-40f

(f) A sea daisy (class Concentricycloidea)


Chordates

• Phylum Chordata consists of two subphyla of invertebrates as well as hagfishes and vertebrates

• Chordates share many features of embryonic development with echinoderms, but have evolved separately for at least 500 million years


You should now be able to:

1. List the characteristics of the phylum “Porifera”

2. List the characteristics of the phylum Cnidaria that distinguish it from other animal phyla

3. List the characteristics of Platyhelminthes

5. List the characteristics of Mollusca

6. List the characteristics of Annelida

7. List the characteristics of Nematoda

9. List three features that account for the success of Arthropods

10. Describe the developmental similarities between echinoderms and chordates

chapter 33

Documents

pearson education

body layers

basal animals

true tissuessponges

true organshttp

body plan

marine annelidfig

marine flatworma rotifer