Kingdom Anamalia

Characteristics of Animals

• Multicelled heterotrophic eukaryotes

• Require oxygen for aerobic respiration

• Reproduce sexually, and perhaps asexually

• Motile at some stage

• Develop from embryos

Major Animal Phyla

Chordates

Echinoderms

Arthropods

Annelids

Mollusks

Rotifers

Roundworms

Flatworms

Cnidarians

SpongesMulticelled Ancestry

Radial Ancestry

Bilateral Ancestry

Coelomate Ancestry

Single-celled, protistanlike ancestorsFigure 25.2Page 415

Symmetry

Radial Bilateral Figure 25.3Page 416

dorsal

posterior

ventral

anterior

The Gut

• Region where food is digested and then absorbed

• Saclike gut– One opening for taking in food and

expelling waste

• Complete digestive system– Opening at both ends; mouth and anus

Body Cavities - Acoelomate

epidermisgut cavity

no body cavity; region between gut and body wall packed with organs

Figure 25.4aPage 417

Body Cavities - Pseudocoel

epidermis gut cavity

unlined body cavity (pseudocoel) around gut

Figure 25.4bPage 417

Body Cavities - Coelom

gut cavity

peritoneumlined body cavity (coelom) Figure 25.4c

Page 417

Body Cavities - Coelom

gut cavity

peritoneumlined body cavity (coelom) Figure 25.4c

Page 417

Animal Origins

• Originated during the Precambrian (1.2

billion - 670 million years ago)

• From what? Two hypotheses:

– Multinucleated ciliate became

compartmentalized

– Cells in a colonial flagellate became

specialized

Kingdom Anamalia

• Multicellular• Heterotrophic• Sexual reproduction • Produce gametes in sex organs, gonads• 95% lack a backbone and are called

invertebratees• Vertebrates aare a subphylum within the phylum

chordata• Aquatic and terrestrial• tissues organized into organs

Internal Organization

The Protostomes

Molluscs (Phylum Mollusca): shellfish such as clams and limpets, snails, slugs, octopus, and squid.

segmented worms (Phylum Annelida): earthworms, many marine worms that may be free-swimming or live in tunnels or tubes, and leeches

arthropods (Phylum Arthropoda): the most diverse group of animals, which includes insects, spiders, scorpions, ticks, mites, centipedes, millipedes, and crustaceans (aquatic organisms like shrimp and lobster.)

Phylum Mollusca

Mollusks have 3 body regions: a head, a visceral mass, and a "foot.“

• Bilateral, soft-bodied, coelomate

• Most have a shell or reduced version of one

• Mantle drapes over body and secretes shell

• Most have a fleshy foot

• Many have a radula for shredding food

Mollusks: Phylum Mollusca

• Gastropods

• Chitins

• Bivalves

• Cephalopods

Molluscan Diversity

• Twisting of body parts during larval development

• Occurs only in gastropods

Torsion

mouth

anusgill

Figure 25.18Page 426

Body Plan of a Snail

gillanus

radula

foot

mantle cavity

digestive gland

mantle

heart

Figure 25.18Page 426

Body Plan of a Clam

mouthretractor muscle

left mantle

retractor muscle

foot

palpsleft gill shell

Figure 25.21Page 429

The coelom is a body cavity, within which internal organs can develop, which is completely lined with a middle layer of tissue in the body called mesoderm and distinct from the outer layer that makes up the skin (the ectoderm tissue) and the inner layer that makes up the digestive tract (the endoderm tissue.)

Class Amphineura“Chitons”

Characteristics

• Eight dorsal plates

• Reduced head

• One Foot

• Radula for scraping rocks

Class Gastropoda“Snails, limpets, abalones, slugs”

Spiraled Shell

Class Bivalvia (Cephalopoda)“clams, oysters and mussels”

Bivalvia

• Shell of two valves

• Head Reduced

• Gills

• No radula and filter feeders

Class Cephalopoda“Squid,octopi, chambered nautilus”• Shell external, internal or absent

• Foot modified into eight arms and some with two tentacles

• mantle muscular and forms a siphon for “jet” propulsion

• radula modified as a beak

• excellent vision

• All marine

Cuttlefish Body PlanClosed circulatory system with heart and

accessory heart

stomachkidneyesophagus

digestive gland

brain

arm

jaw

tentacle radula

siphon

anusink sac

gillheart accessory

heart

reproductive organ

mantleinternal

shell

Figure 25.22Page 429

http://www.wpunj.edu/cos/envsci-geo/ceph_diagram.htm

Segmented, coelomate worms

• Class Polychaeta

• Class Oligochaeta

• Class Hirudinea

Annelids: Phylum Annelida

Phylum Annelida“segmented worms”

Class Polycheata“Bristle Worms”

• Many setae born on parapodia

• Relatively well devloped head

• Sedentary (tube dwelling)

• Errant (Swimmers or crawlers

• All are marine

Polychaetes

• Most are marine• Bristles extend

from paired, fleshy parapods on each segment

• Head end is specialized

Fig. 25.24cPage 430

“jaws”

toothlike structurespharynx (everted)antenna

palp (food handling)

tentacle

eyes

chemical-sensing pit

parapod

Class Oligochaeta“Earthworms and Freshwater

Annelids”

• Few setae borne on parapodia

• Reduced head

• Terrestrial and Fresh water

No parapodia, few bristles per segment

Earthworm - An Oligochaete

Nerve cord

Nerve cord

Dorsal blood vessel

Nephridium

Coelom

Circular muscle

Longitudinal muscle

Seta (retracted)Figure 25.25a

Page 431

Earthworm Nephridiumbladderlike storage region of nephridium

nephridium’s thin loop reabsorbs some solutes, relinquishes them to blood

blood vessels

body wall

external pore (fluid containing wastes discharged here)

funnel (coelomic fluid with waste enters here)

Figure 25.25bPage 431

Earthworm Circulatory System

Hearts

Figure 25.25cPage 431

Earthworm Digestive System

PharynxEsophagus

Crop Gizzard

Coelomic chambers

Mouth

Figure 25.25dPage 431

Earthworm Nervous System

Brain

Nerve cord Figure 25.25ePage 431

Class Hirudinea“Leeches”

• Body Flattened

• Anterior and Posterior Suckers

• Constant number of segments (32 or 33)

• Predatory or parasitic

• Anticoagulant

• No setae

• Most freshwater, Few terrestrial

• Predators and parasites

• Less obvious body segmentation

• Most have sharp jaws

Leeches - Class Hirudinea

http://www.biokids.umich.edu/resources/spring2002/1019605760.jpg/view.html