Chapter 33 Invertebrates PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc.

Transcript Chapter 33 Invertebrates PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc.

Chapter 33 Invertebrates

PowerPoint Lectures for

Biology, Seventh Edition Neil Campbell and Jane Reece

Lectures by Chris Romero

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Kingdom Animalia

Overview: Life Without a Backbone • Invertebrates – – Are animals that lack a backbone Account for 95% of known animal species

Figure 33.1

Animal phylogeny

Figure 33.2

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Porifera

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Porifera

· Asymmetrical • · Sessile • · Filter (Suspension) Feeders • · 5000 salt water species 150 fresh water spp • · No tissues, organs, or organ systems • · Reproduce sexually (Most are hermaphrodites) or asexually (Budding/Fragmentation) • · Believed to have evolved from protists Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Porifera

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.

Flagellum Collar Food particles in mucus Choanocyte

Figure 33.4

Azure vase sponge

(Callyspongia plicifera)

4 Spongocoel.

Water passing through porocytes enters a cavity called the

3 Porocytes.

spongocoel.

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.

Water flow

1 Mesohyl.

The wall of this simple sponge consists of two layers of cells separated by a gelatinous matrix, the mesohyl (“middle matter”).

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).

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Porifera

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Cnidaria

Cnidarians have radial symmetry, a gastrovascular cavity, and cnidocytes • All animals except sponges – Belong to the clade Eumetazoa, the animals with true tissues • Phylum Cnidaria – Is one of the oldest groups in this clade Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Cnidaria

Radial Symmetry (Diploblastic) Made of only 2 layers of cells (Outer layer for protection, inner layer for digestion) 9000 species e.g. jellyfish, coral, sea anemones, hydra Have two forms (Sessile polyp and mobile medusa) Has a simple nerve net…1 st animals organized nervous tissue in Reproduce sexually and asexually (budding) 1 st predators 1 st digestive cells (Gastrovascular cavity) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Cnidaria

The 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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Cnidaria

There are two variations on this body plan – The sessile polyp and the floating medusa

Polyp

Mouth/anus

Medusa

Tentacle Gastrovascular cavity Gastrodermis Mesoglea Epidermis Body stalk Tentacle Mouth/anus

Figure 33.5

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Cnidaria

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 Prey Tentacle Nematocyst

Figure 33.6

Cnidaria classes

Table 33.1

Cnidaria

– Hydrozoa, Scyphozoa, Cubozoa, and Anthozoa (a) These colonial polyps are members of class Hydrozoa.

Figure 33.7a–d

(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.

Hydra Anemone

Hydra

• 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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Protostome vs Deuterostome Differentiation

Spiral vs Radial Cleavage

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Flatworms

Members of phylum Platyhelminthes – – Live in marine, freshwater, and damp terrestrial habitats Are flattened dorsoventrally and have a gastrovascular cavity • Although flatworms undergo triploblastic development – They are acoelomates Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Flatworms

Bilateral symmetry • Phylum Platyhelminthes • 14 500 species e.g. Tapeworms, flukes, planaria • 1 st animal with nerve cord • 1 st animal with defined head (planaria) • 1 st animal with a pharynx (throat) • Have only one opening to the body (pharynx) • Planarians can regenerate (cut in half and each half will regenerate) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Reproduce sexually (most are hermaphroditic) or asexually (regeneration)

Flatworms are divided into four classes

Table 33.2

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Turbellarian

Turbellarians – Are nearly all free-living and mostly marine

Figure 33.9

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Planaria

The best-known turbellarians, commonly called planarians – 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 gastro vascular cavity, which has three branches, each with fine subbranches that pro vide an extensive surface area.

Undigested wastes are egested through the mouth.

Gastrovascular cavity Eyespots

Figure 33.10

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.

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Flukes

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Tapeworm

Tapeworms – –

Scolex

parasitic lack a digestive system Scolex Hooks Sucker

Figure 33.12

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Rotifers

Rotifers are smaller than many protists – But are truly multi-cellular and have specialized organ systems

1 st alimentary canal Separate mouth & anus Figure 33.13

0.1 mm

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Rotifers

Rotifers have an alimentary canal – A digestive tube with a separate mouth and anus that lies within a fluid-filled pseudocoelom Rotifers reproduce by parthenogenesis – In which females produce more females from unfertilized eggs Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Nemerteans

Members of phylum Nemertea – Are commonly called proboscis worms or ribbon worms

Figure 33.15

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Nemerteans

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 Have no heart Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• Mollusca Molluscs have a muscular foot, a visceral mass, and a mantle • Phylum Mollusca – Includes snails and slugs, oysters and clams, and octopuses and squids • 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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Phylum Mollusca

• • • • • • • Bilateral symmetry 3 classes (Gastropoda, Bivalvia, Cephalopoda) Gastropods (Stomach footed) e.g. Periwinkles, slugs, snails, & conches Bivalves (Two shells) e.g. Clams, oysters, and scallops have two shells connected by a ligament Cephalopods (Head footed) e.g. Octopi, Squid Coelomates Have digestive tract with mouth and anus • • · · 1 st animals with simple brain and paired complex eyes 1 st open circulatory system with 2 or 3 chambered heart • • · · Respiration through gills Excretion of metabolic wastes through nephridia • Reproduce sexually (Many are hermaphroditic) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Molluscs

All molluscs have a similar body plan with three main parts – – – A muscular foot A visceral mass A mantle Membrane surrounding internal organs Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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.

Mantle

Mantle cavity The nervous system consists of a nerve ring around the esophagus, from which nerve cords extend.

Anus Gill

Foot Figure 33.16

Visceral mass

Coelom Intestine Gonads Stomach Shell Radula Nerve cords Esophagus Mouth Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The long digestive tract is coiled in the visceral mass.

Mouth Radula. The mouth region in many mollusc species contains a rasp-like feeding organ called a radula. This belt of backward curved teeth slides back and forth, scraping and scooping like a backhoe.

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Mollusca

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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

4 Classes of Mollusca

Table 33.3

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Chitons

Class Polyplacophora is composed of the chitons – Oval-shaped marine animals encased in an armor of eight dorsal plates

Figure 33.17

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Gastropods

About three-quarters of all living species of molluscs – Belong to class Gastropoda

(a) A land snail Figure 33.18a, b (b)

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Gastropods

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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Gastropods

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 Stomach Mantle cavity Intestine Anus Mouth

Figure 33.19

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Bivalves

Molluscs of class Bivalvia – – Include many species of clams, oysters, mussels, and scallops Have a shell divided into two halves Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 33.20

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Bivalves

The mantle cavity of a bivalve – Contains gills that are used for feeding as well as gas exchange Mantle Shell Mouth Hinge area Gut Coelom Heart Adductor muscle Anus Excurrent siphon Palp

Figure 33.21

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Cephalopods

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Cephalopods

Most octopuses – Creep along the sea floor in search of prey

Figure 33.22a

(a) Octopuses are considered among the most intelligent invertebrates.

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Cephalopods

Squids use their siphon – To fire a jet of water, which allows them to swim very quickly

Figure 33.22b

(b) Squids are speedy carnivores with beaklike jaws and well-developed eyes.

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`

One small group of shelled cephalopods – The nautiluses, survives today

Figure 33.22c

(c) Chambered nautiluses are the only living cephalopods with an external shell.

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Annelids

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Phylum Annelida

Bilateral symmetry & Coelomates 15 000 species e.g. Earthworm, leeches Digestive tube with mouth and anus 1 st gizzard (Used to grind food) 1 st developed central nervous system (Ventral nerve cord connects brain to EACH segment) Closed circulatory system Have chaetae (setae) for locomotion Have nephridia to eliminate metabolic waste Reproduce sexually (most are hermaphroditic) Segmentation is important in the evolution of specialized body tissues

The phylum Annelida is divided into 3 classes

Table 33.4

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Oligochaetes

Oligochaetes (class Oligochaeta) – – Are named for their relatively sparse chaetae, or bristles made of chitin Include the earthworms and a variety of aquatic species Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Annelida

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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Polychaetes

Members of class Polychaeta – Possess paddlelike parapodia that function as gills and aid in locomotion

Parapodia Figure 33.24

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Leeches

Members of class Hirudinea – Are blood-sucking parasites, such as leeches

Figure 33.25

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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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Phylum Nematoda

Bilateral symmetry • 12 000 species • 1 st tubular digestive system • 1 st animal with 2 body openings (mouth & anus) • Pseudocoelomates • Ascaris – found in soil. Eggs enter human children’s mouth, develop in the intestines, enter the bloodstream and travel to the lungs. Adults are coughed up and swallowed.

Ascaris

· Pinworms – Most common roundworm infection in the U.S. Eggs are ingested (usually by children) and develop in the intestines. Adult females exit child’s anus while child sleeps. Symptoms of infection are an itchy anus · Trichinella – Found in undercooked pork or wild game Trichinella Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

· Hookworm – common in warm climates. Found in contaminated soil and enters the body through the feet when people walk barefooted. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Nematoda

The cylindrical bodies of nematodes (phylum Nematoda) – Are covered by a tough coat called a cuticle 25 µm

Figure 33.26

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Arthropoda

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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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General Characteristics of Arthropods

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Arthropods

Early arthropods, such as trilobites – Showed little variation from segment to segment

Figure 33.28

· · · · · · · · Bilateral symmetry Coelomates All are segmented 1 st animal with jointed appendages · · · All have an exoskeleton Exoskeleton pros: External protection, support for muscle attachment Exoskeleton cons: They are heavy, limit movement, can’t grow, limits size of organism, arthropod must molt [Ecdysis] (New exoskeleton is soft and does not protect against predators) Have 3 fused body segments (Head, thorax, and abdomen) Have complete digestive system including specialized mandibles (Jaws) Have open circulatory system with a heart Use spiracles and tracheal tubes for respiration Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

· · Use malpighian tubules for excretion of metabolic wastes · Nervous system includes brain, nerve cord, simple or compound eyes, and antennae. Simple eyes have one lens, compound eyes have many lenses. · · · · Antennae are used to detect motion, sound, and to smell (Pheromones) · Reproduction is sexual (Two types of development: Metamorphosis and Incomplete metamorphosis) Metamorphosis includes 4 stages (Egg  Larva  Pupa  Incomplete metamorphosis includes 3 stages (Egg  Adult) Nymph  Adult) Evolved from annelids Classes of arthropods include: Arachnida (Spiders, mites, ticks, & scorpions), Crustacea (Crabs, lobsters, shrimp, crayfish, & barnacles), and Insecta Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Arthropods

As arthropods evolved – The segments fused, and the appendages became more specialized The appendages of some living arthropods – Are modified for many different functions Antennae (sensory reception) Cephalothorax Abdomen Head Thorax Swimming appendages

Figure 33.29

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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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Arthropods

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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Molecular evidence now suggests

– That living arthropods consist of four major lineages that diverged early in the evolution of the phylum

Table 33.5

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Cheliceriforms

Cheliceriforms, subphylum Cheliceriformes – – Are named for clawlike feeding appendages called chelicerae Include spiders, ticks, mites, scorpions, and horseshoe crabs Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Cheliceriformes

Most of the marine cheliceriforms are extinct – But some species survive today, including the horseshoe crabs

Figure 33.30

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Cheliceriformes

Most modern cheliceriforms are arachnids – A group that includes spiders, scorpions, ticks, and mites 50 µm

(a)

Scorpions have pedipalps that are pincers specialized for defense and the capture of food. The tip of the tail bears a poisonous stinger.

Dust mites are ubiquitous scavengers in human dwellings but are harmless except to those people who are allergic to them (colorized SEM).

Web-building spiders are generally most active during the daytime.

Figure 33.31a–c

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Arachnids

Arachnids have an abdomen and a cephalothorax – Which has six pairs of appendages, the most anterior of which are the chelicerae Digestive gland Intestine Heart Stomach Brain Ovary Eyes Poison gland Anus

Figure 33.32

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Myriapods

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Myriapods

Millipedes, class Diplopoda – Have a large number of legs • Each trunk segment – Has two pairs of legs

Figure 33.33

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Myriapods

Centipedes, class Chilopoda – – Are carnivores with jaw-like mandibles Have one pair of legs per trunk segment

Figure 33.34

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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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• • Flight is obviously 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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Insect Development

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 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Insect Development

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

(a) Larva (caterpillar) (b) Pupa (c) Pupa (d) Emerging adult (e) Adult

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Crustaceans

While arachnids and insects thrive on land – Crustaceans, for the most part, have remained in marine and freshwater environments Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Crustaceans

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Crustaceans

Decapods are all relatively large crustaceans – And include lobsters, crabs, crayfish, and shrimp

Figure 33.38a

(a)

Ghost crabs (genus Ocypode) live on sandy ocean beaches worldwide. Primarily nocturnal, they take shelter in burrows during the day.

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Crustaceans

Planktonic crustaceans include many species of copepods – Which are among the most numerous of all animals

Figure 33.38b

(b)

Planktonic crustaceans known as krill are consumed in vast quantities by whales.

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Crustaceans

Barnacles are a group of mostly sessile crustaceans – Whose cuticle is hardened into a shell

(c)

The jointed appendages projecting from the shells of these barnacles capture organisms and organic particles suspended in the water.

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Echinoderms

• Characteristics of deuterostomes – – Radial cleavage Development of the coelom from the archenteron – Formation of the mouth at the end of the embryo opposite the blastopore Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Echinoderms

Sea stars and most other echinoderms – Are slow-moving or sessile marine animals • A thin, bumpy or spiny skin – Covers an endoskeleton of hard calcareous plates Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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Echinoderms

Unique to echinoderms is a water vascular system – A network of hydraulic canals branching into tube feet that function in locomotion, feeding, and gas exchange

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.

Figure 33.39

Stomach Spine Gills 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.

canal Gonads Radial nerve

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.

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Echinoderms

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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

Figure 33.40a

(a) A sea star (class Asteroidea)

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Brittle Stars

A brittle star (class Ophiuroidea)

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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

Figure 33.40c

(c) A sea urchin (class Echinoidea)

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Sea Cucumbers

Sea cucumbers – – Upon first inspection do not look much like other echinoderms Lack spines, and their endoskeleton is much reduced

Figure 33.40e

(e) A sea cucumber (class Holothuroidea)

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Chordates

Chordates

– – – Phylum Chordata Consists of two subphyla of invertebrates as well as the hagfishes and the vertebrates Shares many features of embryonic development with echinoderms Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

• A summary of animal phyla

Table 33.7