Adapted from Lesser Known Protostome Phyla SICB 2001
Adapted from Lesser Known Protostome Phyla. SICB 2001. J. R. Garey. Porifera Cnidaria Ctenophora Platyhelminthes Gastrotricha Gnathostomulida Cycliophora Rotifera Annelida Mollusca Sipuncula Nemertea Bryozoa Brachiopoda Phoronida Arthropoda Onychophora Tardigrada Nematomorpha Nematoda Priapulida Kinorhyncha Loricifera Echinodermata Hemichordata Chordata
Deuterostomes • Platyhelminthes to Ecdyosozoa = Protostomes (first mouth) • Deuterostomes have “second mouth” embryological development – P. Echinodermata – P. Hemichordata – P. Chordata • sub. P Urochordata • sub. P. Cephalochordata • sub. P Vertebrata
Phylum Echinodermata • = spiny skin • Radial symmetry (pentaradial) • Hydrostatic skeleton for locomotion and internal transport – Water vascular system • Coelomates • Triploblastic • Complete digestive tract
P. Echinodermata C. Crinoidea C. Asteroidea C. Ophiuroidea C. Echinoidea C. Holothuroidea C Ancestral echinoderm E A O H
Ancestral echinoderms ~ Crinoids
C. Crinoidea: • • • sea lilies (stalked) motile feather stars (non-stalked) Fossils date back 600 my Oral surfaces upward Filter feeders: trap food in mucus and transported to ambulacral grooves • Tube feet: transport of food, gas exchange, N-excretion
C. Asteroidea: Sea stars 09: 44 BIO 2121 Animal Form and Function 7
Echinoderm surfaces Tube feet and ambulacral groove Aboral surface Oral surface
Water vascular system Madreporite Stone canal Ring canal Radial canal Lateral canal Tube feet
Tube feet extend from ambulacral groove
Sea star arm Spine Ossicle Coelom Tube foot Ambulacral groove
Tube foot Ampulla Lateral canal Body wall Tube foot Retractor muscles Podial muscle Sucker
Movement of tube feet
Pedicellaria Spine Pedicellaria Dermal branchia
Feeding 09: 44 BIO 2121 Animal Form and Function 15
Gonad Anus Pyloric stomach Cardiac stomach Mouth Pyloric cecum
Complete digestive system Anus Pyloric stomach Cardiac stomach Pyloric cecum
Ophiuroidea: Brittle stars 09: 44 BIO 2121 Animal Form and Function 18
Brittle star
Ophiuroidea: Basket stars 09: 44 BIO 2121 Animal Form and Function 20
Ophiuroidea • Most diverse class of echinoderms (2100 spp) • Ambularcral groove is covered by plates • Suspension feeders or ambush predators • Move by lifting legs, not creeping on tube feet
Brittle star Mouth Plates covering abulacral groove
Echinoidea: Sea urchin 09: 45 BIO 2121 Animal Form and Function 23
Water vascular system Madreporite Axial organ Ring canal Radial canal Tube feet
Echinoid spines
Echinoidea: Sand dollars 09: 45 BIO 2121 Animal Form and Function 26
Sand dollar Gonopore Madreporite Ambulacral region Lunule
Holothuroidea: Sea cucumbers Madreporite Cloaca Tentacles Intestine Respiratory tree
Adapted from Lesser Known Protostome Phyla. SICB 2001. J. R. Garey. Porifera Cnidaria Ctenophora Platyhelminthes Gastrotricha Gnathostomulida Cycliophora Rotifera Annelida Mollusca Sipuncula Nemertea Bryozoa Brachiopoda Phoronida Arthropoda Onychophora Tardigrada Nematomorpha Nematoda Priapulida Kinorhyncha Loricifera Echinodermata Hemichordata Chordata
This is on the final exam – be able to redraw it and explain the progression Urochordata Cephalochordata Agnatha Gnathostomes Hemichordata Active filter feeding with internal fenestrated pharynx, dorsal hollow nerve cord Lack notochord Vertebrata Pedomorphosis Pharyngeal slits, post anal tail, notochord dorsal hollow nerve cord, endostyle Passive arm filter feeding (~crinoid echinoderm)
P. Chordata sub. P. Urochordata Mouth Atrium Pharyngeal slits Stomach
Urochordate larva Incurrent siphon Excurrent siphon and anus Dorsal tubular nerve cord Notochord Pharyngeal slits Postanal segments (Tail)
Urochordate metamorphosis
Pedomorphosis/Neoteny • Retention of larval trait past the point of sexual maturity – Either retard somatic development or accelerate gonadal maturity
Pharyngeal slits
Dorsal nerve chord
Notochord
Metameric segmentation Postanal segments (Tail)
Cephalochordata Notochord Nerve cord Tail Mouth Pharyngeal slits Atriopore Anus
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