Animal Kingdom

Animal

• Multicellular eukaryote

• Heterotrophic

• Diploid life cycle

Colonial Flagellate Hypothesis

Multicellular animals evolved from colonies of unicellular, flagellated protists that specialized and integrated into a single organism

Animal Criteria

• Organization

• Body plan

• Type of symmetry

• Type of coelom

• Developmental pattern

Sac Plan

Incomplete digestive system

-one opening used for both entrance and exit

Tube Within a Tube Plan

Complete digestive system

-separate entrance and exit to digestive system

Acoelomate

No body cavity

-flatworms, ribbon worms, tapeworms

Pseudocoelomate

False body cavity

-round worms

Coelomate

Body cavity

-molluscs, annelids, arthropods, echinoderms, chordates

Protostome

Mouth forms first

-molluscs, annelids, arthropods

Deuterostome

Anus forms first

-echinoderms, chordates

Sponge

• Most basic, no true tissues

• Saclike bodies

• Asexual reproduction by fragmentation or budding

• Beating of flagella produces water currents that flow through pores into central cavity and out osculum

• Sessile filter feeders

Germ Layers

Ectoderm, endoderm, mesoderm

Cnidarians

• Tubular, radial symmetry

• Shallow marine water

• Polyp and medusa body forms

• Stinging cells (cnidocytes)

• 2-layered body sac- epidermis and gastrovascular cavity

• Nerve net throughout body

Ribbon Worm - Nemertea

• Distinctive proboscis (nose/snout)

Flatworm - Platyhelminthes

• Majority parasitic

• Organ-level organization

• No circulatory or respiratory structures

• Ladder type nervous system

• Cephalization- nervous tissue and sensory organs in the head

Free-Living Flatworm - Planarians

Freshwater

• Arrow shaped head with sense organs and eye spots

• 3 muscle layers- outer circular, inner longitudinal, diagonal

• Excretory organ functions in osmotic regulation and water excretion

• Asexual reproduction

• Hermaphroditic

Tapeworms

• Parasitic flatworms

• Attach to intestinal wall of host

• Segments each contain both male and female sex organs

Round Worm - Nematoda

• Pseudocoelomates

• Non-segmented

• Colorless

Molluscs

• Coelomates

• 3-part body plan

• Mantle- secrete shell and contribute to development of gills and lungs

• Visceral mass- contains internal organs

• Foot- muscle adapted for locomotion, attachment, and food capture

• Nervous system

• reduced coelom around heart

• Heart pumps hemolymph

Molluscs Types

• Gastropods- snails, slugs

• Bivalves- oysters, clams, scallops, mussels

• Cephalopods- octopuses, squids

Annelids

• Segmented worms

• Coelomates

• Digestive tract

• Closed circulatory system

• Nerve cord

• Marine

• Setae help in movement

Annelids- Polychaetes

• Many setae

Annelids- Oligochaetes

• Few setae

• Earthworms

• Hermaphroditic

• Body rings

• Coelom divided by septa

Arthropods

• Freely movable jointed appendages

• Hard cuticle exoskeleton

• Molt to grow

• Segments fused into regions

• Head, thorax, abdomen

• Metamorphosis

Arthropod Types

• Crustaceans

• Hexapods

• Myriapods

• Chelicerates

Crustaceans

• Decapods- 10 legs

• Respiratory system of gills

• Shrimp, lobsters, crayfish, crab

Hexapods

• Insects

• 6 legs

• Antennae, mandibles, maxillae

• Breathe by trachae

Myriapods

• Centipedes and millipedes

• Many legs

Chelicerates

• Terrestrial spiders, scorpions, ticks, mites, horseshoe crabs, sea spiders

• Appendages attached to cephalothorax

• Chelicerae- feeding organs

• Pedipalps- sensory

Echinodermata

• Starfish, sea urchins, sea cucumbers

• Sessile or slow moving

• Group represents a major change in animal embryonic development

• Deuterostomes- anus forms first

• Bilateral symmetry

• Closest relatives to vertebrates

• Endoskeleton and complete digestive system

Chordates

• Notochord

• Nerve cord

• Pharyngeal pouches

• Tail

Invertebrate Chordates

• Notochord persists and is never replaced by a vertebral column

• Lancelets

• Sea squirts

Vertebrate Features

• Endoskeleton with vertebral column

• Closed circulatory system

• Paired appendages

• Cephalization

Ctenophora and Cnidarians

• 2 tissue layers- only develop endoderm and ectoderm

• Radial symmetry