Test 3 - Phylum: Echindermata echinoderms (spiny-skin); sea...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Phylum: Echindermata echinoderms (spiny-skin); sea stars, sea urchins, sea cucumbers, sea lilies A. All marine (poor osmoregulators), 6,000 or so extant species B. Deuterostomous, enterocoelous, triploblastic, eucoelomate C. Secondarily evolved radial symmetry—embryos are bilaterally symmetrical D. Sessile lifestyle favors radial symmetry shown in adults Often pentaradial symmetry A. B. Class Ophiuroidea- brittle stars, largest in species and total number among echinoderms a. Pentaradial symmetry b. No pedicellarie, no popular, no anus c. Tube feet used for respiration and often feeding, but no locomotion, are all over their body. i. No suckers on tube feet ii. Move really fast d. Arms are narrow and distinct from the body i. Articulated ossicles form joints in arms for movement 1. Often very mobile e. Genitorespiratory bursa at body margins between arms on oral side i. Gasses exchange here ii. Egg released and fertilized here and young often brood here f. Detritivores or filter-feeders (e.g. basket stars) i. Tube feet around mouth bring in food particles g. Excellent regenerators; some able to reproduce asexually by cleaving the body disk i. Autotomize limbs readily C. Class Echinoidea - sea Urchins, sand dollars (la del lab que hacia un ruido – Blanca-bilateral symmetry) a. Dermal ossicles as fused plates make up test (skeleton) like internal skeleton i. Long protruding spines for movement defense b. Pentaradial symmetry without arms c. Some groups of “irregular” urchins have become secondarily bilateral (biradial) almots radial… d. Some move using their tube feet. . e. Pedicellariae present for cleaning and prey capture (some are Toxic)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
f. Aristotle’s lantern- 5 part chewing structure around the mouth of sea urchins i. Grazers of algae or detrivores D. Class Holothuroidea- sea cucumbers a. Greatly elongated along oral- aboral axis, biradial symmetry i. Adapted for burrowing r crawling along bottom b. Very soft bodied with much reduced ossicles (usually) c. Movement using tube feet, oral end forward i. Oral tentacles- modified tube feet on oral end for filter feeding or deposit feeding ii. Individual tentacles are stuffed into mouth and sucked clean d. Gas exchange trough skin , tube feet and trough a respiratory tree attached to cloaca i. Water pumped into and out of the anus for oxygen ii. Effectively “water-lung”- habeces sirve para catch predators e. Defensive mechanism include expulsion of respiratory trees and other viscera i. Predator eats or is repulsed (some are toxic) by this and sea cucumbers escapes f. Tienen tube feed E. Class Crinoidea - sea lilies and feather stars a. Oral end upward and attached as filter-feeders for most of their lives i. Often attached by a stalk- casi 100pre estan attached pero de vez en cuando se mueven, separe a ua flor ii. May be able to detach and weakly swim by “flapping arms b. Arms greatly elongated and branches with extensions called pinnules. i. Tube feet on pinnules are covered in as tick
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/28/2010 for the course BIO Bio311c taught by Professor Sathasivan during the Spring '10 term at American College of Gastroenterology.

Page1 / 19

Test 3 - Phylum: Echindermata echinoderms (spiny-skin); sea...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online