A Phylogeny of the Animal Phyla
Porifera
No true tissues
Cnidaria
radial symmetry
diploblastic
Acoelomates
Ctenophora Platyhelminthes
Pseudocoelomates
Rotifera Nematoda Nemertea Protostomes
true tissues
Mollusca Annelida Arthropoda
Bilateral symmetry
triploblastic
Body cavity
Lophophorate phyla
Coelomates
Deuterostomes
Bryozoa Phoronida Brachiopoda Echinodermata Chordata
Echinodermata - the starfish, urchins, sea cucumbers,
sand dollars
Echinodermata - the starfish, urchins, sea cucumbers
• Description Echinoderms are • deuterostomes • have a water vascular system • have hardened plates (ossicles) in their epidermis • pentaradial symmetry
General anatomy of a starfish
General anatomy of a starfish
Ring canal
Anus Cardiac stomach
Madreporite
Ossicles
Stone canal
Pyloric stomach
Mouth
Radial canal
Ring canal Ampulla
Tube foot
Echinodermata - the starfish, urchins, sea cucumbers
Water vascular system - a closed system of canals that echinoderms use for locomotion
Echinodermata - the starfish, urchins, sea cucumbers
Water vascular system - a closed system of canals that echinoderms use for locomotion
Echinodermata - the starfish, urchins, sea cucumbers
Water vascular system - by using water pressure echinoderms can crawl along by moving individual “tube feet” along their bodies
Echinodermata - the starfish, urchins, sea cucumbers
Water vascular system - by using water pressure echinoderms can crawl along by moving individual “tube feet” along their bodies Ampullar muscles Longitudinal muscles
To extend foot 1) Flex ampullar muscle 2) Relax longitudinal muscle 3) Flex circular muscles
Circular muscles
Echinodermata - the starfish, urchins, sea cucumbers
Ossicles
Echinodermata - Who are they?
Asteroidea - Sea stars (starfish) - active predators, with small ossicles in their epidermis
Echinodermata - Who are they?
Echinoidea - Sea urchins - grazers, with ossicles fused to form a test
Echinodermata - Who are they?
Echinoidea - Sand dollars - grazers, with ossicles fused to form a test
Echinodermata - Who are they?
Holothuroidea - Sea cucumbers - bottom feeders, with very reduced (or absent) ossicles
Taxa we have looked at so far Phylum
Class
Porifera
Calcarea Demospongia Hexactinellida
Platyhelminthes
Turbellaria (free-living) Trematoda (flukes) Cestoda (tapeworms)
Mollusca
Polyplacophora (chitons) Gastropoda (snails,slugs) Bivalvia (clams, oysters) Cephalopoda (octopus, squid)
Annelida
Oligochaeta (earthworms) Hirudinea (leeches) Polychaeta (marine worms)
Arthropoda
Chelicerata (spiders, mites, scorpions)
Myriapoda (centipedes, millipedes)
Uniramia (insects)
Crustacea (crayfish, lobsters, crabs, barnacles)
Order
Taxa we have looked at so far Phylum
Class
Echinodermata
Asteroidea (Sea stars [=starfish])
Echinoidea (sea urchins, sand dollars)
Holothuroidea (sea cucumbers
Order
Diversity of Life - Chordata-
Chordata - lancets, sea squirts, vertebrates
• Description Chordates are deuterostomes, with a dorsal hollow nerve cord, gill slits, a post-anal tail and a notochord
Chordata - Chordate evolution - Ancestral forms - Lancet
Worms (Amphioxus) Nerve cord
Notochord
Myomeres
Chordata - Chordate evolution - Ancestral forms - Lancet
Worms (Amphioxus)
Sea Squirts - Urochordates (Tunicates)
Sea Squirts - Urochordates (Tunicates)
Sea Squirts - Urochordates (Tunicates)
Chordate Phylogeny (so far)
Cephalochordata (Amphioxus) Urochordata (tunicates)
Craniata
Chordata - Chordate Evolution
Chordates acquire over time: 1.
A distinct head - Craniates (most are extinct)
2.
A backbone
3.
Jaws
Chordata - Chordate Evolution
Today
Chordata - Chordate evolution - Craniates One surviving group - hagfish - head but no backbone
Chordata - Chordate evolution - Craniates One surviving group - hagfish - Scavengers
Chordata - Chordate evolution - Vertebrates - craniates with a backbone Jawless vertebrates - Agnatha - Lamprey
Chordata - Chordate evolution - Vertebrates - craniates with a backbone Jawless vertebrates - Agnatha – Lamprey - fish parasites
From Craniate to Vertebrate Fibrous sheath Notochord Hagfish Cartilage
Lamprey
Bone Gnathostomes
Next time: Fish and more….
