Major Animal Phyla

Porifera, Cnidaria, Platyhelminthes, Annelida,

Mollusca, Arthropoda, Echinodermata, and Chordata

Phylum Poriferasponges

• Have no definite shape – asymmetrical;• No tissues or organs• Colony of specialized cells• Immobile• Good powers of regeneration• Skeleton of spongin and spicules

CLASSES OF SPONGES

• Class Calcarea – has calcium carbonate spicules

• Class Hexactinellida – glass sponges with spicules of silica

• Class Demospongiae – no spicules, only spongin

SPONGE ANATOMY

Barrel sponge

Vase sponge

Tube sponge

Venus Flower Basket

Phylum Cnidariastinging-celled animals

• Jellyfishes, corals, anemones

• Radial symmetry

• Two tissue layers with inner mesoglea

• Primitive nerve net but no brain

• 2-way digestive tract

• Stinging cells for capturing food.

CLASSES OF CNIDARIANS

• Class Hydrozoa – Hydra, Portuguese-Man-of-War, Obelia; mostly polyp or hydroid stage

• Class Scyphozoa – true jellyfishes; mostly medusa stage

• Class Anthozoa – corals, anemones

• Class Cubozoa – box jellies

CLASS HYDROZOA

Hydra

CLASS SCYPHOZOA

Moon jelly

CLASS ANTHOZOA

Sea anemone

Aggregating anemones

Anemone

Coral polyps

Coral reef

CLASS CUBOZOA

Phylum Platyhelminthesflatworms

• First animals to exhibit bilateral symmetry

• Have primitive brain

• 3 tissue layers

• Includes free-living flatworms and parasitic flatworms (tapeworms, flukes)

CLASSES OF FLATWORMS

• Class Turbellaria – free-living flatworms

• Class Cestoda – tapeworms

• Class Trematoda - flukes

Flatworm

Flatworm

Flatworm

Tapeworm head (scolex)

Liver fluke

Phylum Annelidasegmented worms

• Earthworms, sandworms, leeches

• One-way digestive system

• Have well-developed digestive and circulatory systems

CLASSES OF ANNELIDS

• Class Oligochaeta – earthworms, bloodworms; oligo- means “few” and chaeta means a “bristle” or stout hair

• Class Polychaeta – many bristles and parapodia (fleshly lobes to “walk” with

• Class Hirudinea – leeches (most are NOT bloodsuckers)

Christmas tree worm

Feather-duster worm

Fireworm

Nereis – a polychaete

Oligochaete

Leech

Phylum Mollusca-soft bodied animals

• includes snails, slugs, nudibranchs, chitons, limpets, clams, oysters, squid, octopus, nautilus, etc.

• Either have no shell, one shell, or two shells

• Many have hard mouth parts (radula in gastropods, beak in cephalopods).

CLASSES OF MOLLUSCS

• Class Gastropoda – snails, slugs, conchs, nudibranchs; have either no shell or one shell; name means “stomach foot”

• Class Bivalvia – clams, oysters, mussels; have two shells that hinge together

• Class Polyplacophora – chitons; snail-like with 8 embedded plates on its back

• Class Cephalopoda – squid, octopus, nautilus, cuttlefish; name means “head foot”; well-developed nervous system

Nudibranch

Nudibranch

Nudibranch

Chiton

Chiton

Reef Squid

Cuttlefish

Blue-ring octopus

Chambered nautilus

Triton shell

Oyster on half-shell(needs Tabasco)

Scallop

Phylum Arthropoda – joint-legged animals

• includes insects, crustaceans, centipedes, millipedes, and arachnids

• exoskeleton made of chitin

• must shed shell to grow

CLASSES OF ARTHROPODS

• Class Crustacea – shrimps, lobsters, crabs, crawfishes

• Class Amphipoda – small; called scuds• Class Isopoda – sea lice; some are parasitic• Class Stomatopoda – mantis shrimps• Class Pycnogonida – sea spiders• Class Merostomata – horseshoe crabs• Class Cirripedia - barnacles

Bulldozer larva - Crustacea

Bulldozer

Cleaner shrimpCrustacea

Spider crabCrustacea

Crab zoeacrustacea

Crab megalops

Stone crab

Hermit crab - crustacea

Amphipoda

Giant Isopod

Parasiticisopod

Ligia exotica - isopod

Mantis shrimp - Stomatopoda(thumbsplitter)

Horseshoe crabMerostomata

Sea spider- Pycnogonida

Barnacles - Cirripedia

Phylum Echinodermata –spiney-skinned animals

• includes sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers, and crinoids

• reverted back to radial symmetry (radial in adults / bilateral in larvae)

• tube feet and water vascular system

• Most exhibit pentamerism

WHY ARE ECHINODERMS RANKED SO HIGH?

• Clues from embryology – study of the early development of animals

• Protostomes versus Deuterostomes

• Protostome – blastopore forms the mouth in all animals except echinoderms and chordates

• Deuterostomes – blastopore forms the anus in echinoderms and chordates

CLASSES OF ECHINODERMS

• Class Asteroidea – sea stars

• Class Ophiuroidea – brittle stars, serpent stars

• Class Echinoidea – sea urchins, sand dollars

• Class Holothuroidea – sea cucumbers

• Class Crinoidea – sea lilies, feather stars

Sea star - Asteroidea

Bat star - Asteroidea

Pycnopodia - Asteroidea

Brittle star - Ophiuroidea

Sea urchin - Echinoidea

Purple urchinsEchinoidea

Sand dollar - Echinoidea

Sea cucumberHolothuroidea

Feather star - Crinoidea

Phylum Chordata

• Includes fish, amphibians, reptiles, birds, and mammals

• Chordate characteristics:

• Dorsal hollow nerve tube

• Notochord

• Pharyngeal gill slits

• Post anal tail

CHORDATE CLASSIFICATION

• The Protochordates - invertebrate chordates

• Subphylum Urochordata – sea squirts, salps, and ascidians

• Subphylum Cephalochordata – lancelets

• True Chordates:

• Subphylum Vertebrata

Tunicate - Urochordata

Tunicate - Urochordata

Salp- Urochordata

CEPHALOCHORDATEAmphioxus

SUBPHYLUM VERTEBRATA

• Class Agnatha – jawless fishes; lampreys and hagfishes

• Class Chondrichthys – cartilaginous fishes; sharks, rays, skates, chimeras

• Class Osteichthys – boney fishes• Class Amphibia – frogs, salamanders• Class Reptila – turtles, snakes, lizards, and

crocodilians• Class Aves – birds• Class Mammalia - mammals

VERTEBRATE BODY PLAN

• Recapitulation Theory – Ontogeny recapitulates Phylogeny

• The embryological and developmental changes an organism goes through restates its evolutionary history

• Evolution cannot go back and change history…it can only modify what is pre-existing

Sea lamprey - Agnatha

Hagfish - Agnatha

Great white shark - Chondrichthys

Tiger shark - Chondrichthys

Manta ray - Chondrichthys

Stingray - Chondrichthys

Ratfish (Chimera)- Chondrichthys

Electric ray - Chondrichthys

Leafy sea dragon - Osteichthys

Sargassum fish - Osteichthys

Deep sea angler fish - Osteichthys

Clown anemone fish - Osteichthys

Bull dolphin - Osteichthys

Bullfrog - Amphibia

Green sea turtle Reptila

American alligator - Reptila

Osprey - Aves

Great blue heron - Aves

Humpback whales - Mammalia

Sea lionMammalia