(feather star) |
(starfish) |
Phylum ECHINODERMATA
(traits and tree after Brusca & Brusca 1990 834;
|
(sea urchin) |
|
(brittle star) |
(sea cucumber) |
==1================================= Crinoidea (sea lilies, feather stars) <<=E====| | ==4=============== Asteroidea ('true' starfish) | ====3====| | | ==5=============== Ophiuroidea (brittle stars) $ ===2=====| | ==7=============== Echinoidea (sea urchins) ====6====| ==8=============== Holothuroidea (sea cucumbers)
$ some consider the Ophiuroidea to be the sister group of the Echinozoa based on the ambulacra
Back to Zool 250 tree for animal phyla or Deuterostomia.
TRAITS SUPPORTING EACH CLADE (** plesiomorphic- a primitive state, not unique to clade) AND HIGHER TAXA:
b) endoskeleton of calcareous ossicles with unique perforated structure (stereom) c) unique water vascular system with suckerless podia d) open ambulacral grooves e) mouth & anus on oral surface** f) sessile; attached to substratum with aboral surface (primitively) g) multiple gonads** # h) spherical sperm** # i) gill pores/slits absent in adults j) mutable collagen tissue k) monociliated cells** l) dipleurula larvae** b) multiple arms bearing open ciliated grooves for suspension feeding c) podia lack suckers**, not used for locomotion d) ring canal has many stone canals e) use articulated cirri for locomotion (derived forms) f) vitellaria larvae b) oral surface becomes ventral c) anus becomes dorsal d) use podia (tube feet) for locomotion e) stone canal becomes ossified # f) polian vesicles (or similar) on ring canal b) eyespot at each arm tip c) podia possess suckers d) pedicellaria** (2 orders) e) paired pyloric cecae in each arm f) gonads in arms g) bipinnaria & brachilaria larvae |
b) arm ossicles like miniature 'vertebrae' c) oral madreporite d) anus absent in adult e) ophiopleuteus larvae b) ambulacral grooves extend from oral to aboral pole c) aboral surface restricted to small region around anus d) podia possess suckers e) podia possess calcified disc # f) podia possess secretory goblet & tuft cells # g) esophagous has internal skeleton # h) well developed hemal system b) test covered with articulated, moveable spines; spines quite large in some taxa c) pedicellaria** (all orders) d) Aristotle's lantern e) secondary bilateral symmetry (some groups) f) Polian vesicles lost (replaced by Tideman's bodies) g) elongate sperm h) echinopleuteus larvae b) fleshy body c) elongation of body along oral-aboral axis d) oral podia modified as particle feeding tentacles e) secondary bilateral symmetry (some groups) f) paired, internal respiratory trees g) single gonad # h) auricularia larvae |
# traits from Janies 2001