Echinoderms and Chordates e/zo150/mozley/fall/studyaids.h tml

Figure ANCESTRAL PROTIST Porifera Ctenophora Cnidaria Acoela True Tissues Metazoa Eumetazoa Bilateria Hemichordata Echinodermata Chordata Platyhelminthes Rotifera Ectoprocta Brachiopoda Mollusca Annelida Nematoda Arthropoda Deuterostomia Lophotrochozoa Ecdysozoa Single common animal ancestor Only phylum containing vertebrates protostomes invertebrates Bilateral & 3 germ layers

Deuterostomes Radial cleavage Blastopore = anus Mesoderm from distal end of archenteron (Mesodermal endoskeleton)

Echinodermata Feather star

Echinoderms Pentamerous radial symmetry at full development – (bilateral as larvae) Water vascular system Endoskeleton (CaCO3) covered by thin epidermis (skin) – Ossicles No brain or central nerve cord No separate respiratory and circulatory system No Excretory and osmoregulatory organs Complete digestive tract Typically dioeciously w/ external fertilization – Larval state

5 Classes Asteroidea Ophiuroidea Echinoidea Crinoidea Holothuroidea

Asteroidea

Arms radiating from central disc Tube feet, – Chemical adhesive Seastars = Predators Sea daisies (suspension feeders that use sticky membrane) Everts stomach Can regenerate lost arms

Ophiuroidea (brittle stars) long slender arms That can grip Tube feet (no adhesive) Mouth on underside Filter feeders, scavenger, and predators Feather star

Echinoidea (urchins and sand dollars) No arms Retain 5 rows of feet Elongated spines w/ attached muscles to move them Grazers and filter feeders Ossicles fused into a solid/rigid test Mouth down

Crinoidea (sea lilies and feather stars) Mouth up Feather like arms that radiate upward Filter feed with tubefeet Sea lilies – attached to substrate by a stalk Sea feathers – crawl on substrate with long featherlike arms Feather star

Holothuroidea (sea cucumbers) elongated on short axis No arms “no skeleton” widespread ossicles No spines 5 rows of tube feet those around mouth developed into feeding tentacles

Chordates Deuterostomes, Bilaterally symmetric bodies w/ coelum Segmented/metamerism (somites) Chordate characteristics 1.Dorsal Hollow nerve cord: 2.Notochord (phylum’s namesake) 3.Pharyngeal slits or clefts (not gill) 4.Muscular post-anal tail

Dorsal Hollow Nerve Cord

Cephalachordata (lancelets) Filter feeding larvae  filter feeding “fish-like” – adults up to 6 cm long And retain all major chordate characteristics in maturity Gas exchange occurs across the body surface (not with gills) Myotomes + notochord  swimming Closed circulatory system Protonephridia Dioecious w/ External fert.

Urochordata (tunicates/sea squirts) Sessile filter feeders, or drifting pelagic filter Has chordate characteristics in larval stage – pharyngeal slits only in adult Incurrent siphon  gill slits/pharyngeal basket  atrium  excurrent siphon Waste/anus empties into atrium and out the excurrent siphon Gas exchange across surface Open circulatory system Hermaphroditic w/External fertilization Rapid development with larval stage often lasting only a single day Bilaterally symmetrical