The Echinoderms (Means: spiny + skin + to bear)

1. The Echinoderms (Means: spiny + skin + to bear) Zoology – Chapter 16

2. Phylum Echinodermata characteristics • __________________(anus from blastopore) • __________________symmetry (body parts of 5 or multiples of, arranged around oral-aboral axis) • Calcium carbonate internal skeleton (__________) • __________________________ system • series of water-filled canals • extensions called ____________emerge through ossicles • ________________system • derived from coelom and circulates fluid

3. 5 Classes: • _________________ • sea stars • _________________ • brittle stars, basket stars • _________________ • sea urchins, sand dollars • _________________ • sea cucumbers • _________________ • sea lilies, feather stars

4. Class Asteroidea (_____+ in the form of) • About 1,500 species in marine environments • Brightly colored (red, orange, blue, or grey) • 5 arms that radiate from a central disk

5. Water Vascular System (WVS) • Used for locomotion, feeding, and gas exchange • _________________opens to the outside or to the body cavity through _______________and an opening called the __________________ which serves as a water inlet to replace water lost from the water- vascular system and may help equalize pressure

6. Sea Star Anatomy • Mouth on oral surface • Fixed spines on aboral surface • _____________________or Papulae extend between ossicles (calcium carbonate internal skeleton) and help with gas exchange • ______________– pincherlike structures that clean the body surface of debris and help protect

7. Sea Star Anatomy • _____________________– runs the length of the arm and houses the radial canal and paired rows of tube feet • _____________________– bulblike, muscular sac that helps extend tube feet Side view of one ray of a walking starfish, with tube feet. A single tube foot in motion.

9. Sea Star Feeding • Feed on snails, bivalves, crustaceans, polychaetes, corals, and others (or hand fed scallops) • Mouth short esophagus large stomach short intestine rectal cecae • Stomach = 2 parts • Larger (oral/__________stomach) receives ingested food • Smaller (aboral/_____________stomach) connects to secretory and absorptive structures • Ingest prey whole (digested extracellularly within stomach) then undigested expelled through mouth

11. Nervous System • Coordinates the tube feet so that all feet move sea star in the same direction • _____________________– encircles the mouth and radial nerves that extend into each arm • ____________________lie in the ambulacral groove and coordinate the functions of the tube feet • No brain or ganglia; other sensory elements are in the form of the nerve net • Have specialized sensory receptors to detect light at the tips of their arms (tube feet that lack suction cups = _____________)

12. Asteroidea:Regeneration & Reproduction • Can regenerate any part of a broken arm • Some species can even regenerate an entire sea star from a broken arm • Process can take up to a year to complete • ___________________: • Division of the central disk followed by regeneration • ___________________: • Sexes are indistinguishable externally • 2 gonads present in each arm • External fertilization

13. Class Ophiuroidea (snake + tail + in the form of) • _______________group of echinoderms with over 2,000 species • Long arms sharply off of central disk gives pentagonal shape • _______________dermal banchiae and pedicellariae • Tube feet ______________________ and ampullae • Madreporite on the oral surface • WVS is _____________used for locomotion; skeleton modified to grasp Basket Star Brittle Star (aka–serpent star)

14. Ophiuroidea cont. • Ambulacral groove thought to be “_____________”. • Use arms and tube feet in a sweeping motion to trap prey. Watch a Brittle Star feeding…. • Basket stars are ______________________for plankton. • Mouth is in center of central disk with 5 triangular jaws. • No intestine, no digestive tract extending into arms. • Coelom is reduced and confined to central disk. • Membranous sacs called ____________rid ammonia via diffusion.

15. Watch a Brittle Star move…

16. Ophiuroidea: Regeneration and Reproduction • Can regenerate lost arms. • Some have a __________________across central disk and can split into 2 and regenerate. • Dioecious: • Males are smaller than females • Eggs, fertilization, & development take place in bursa • Larval stage, ___________________, is planktonic and undergoes metamorphosis before sinking to substrate • See a Basket Star spawning…

17. Class Echinoidea (_______________+ in the form of) • 1,000 species in all marine environments • _____________________ • specialized for living on hard substrates • wedge between crevices and holes in rock/coral • ________________________ • live in sand or mud • burrow just below the surface • use tube feet to catch organic material passing over them

18. Sea Urchins • Predator is a sea star • Rounded body • Oral end is oriented toward substrate • Skeleton is called a ______; consists of 10 sets of closely fitting plates that arch between oral and aboral ends • Spines are sharp and hollow; may contain venom that is poisonous to swimmers • Pedicellariae have _____________________

19. Sand Dollar and Heart Urchins • Use spines to burrow • Skeletons found on beaches • Heart urchin - AKA – sea potato (“fattened” sand dollar) • Heart urchin moving • Sand dollar moving Sand dollar & it’s 5 jaws

20. Aristotle’s lantern Echinoidea:Maintenance Functions • Feed on algae, bryozoans, coral polyps, dead animal remains • _______________________is the chewing apparatus and can be projected from mouth • 35 ossicles _________________________________ • mouth – pharynx – esophagus – long coiled intestine – anus • Have a large coelom • Gas exchange through diffusion • Excretory and nervous systems same as Asteroidea

22. Echinoidea:Reproduction and Development • Dioecious • Gonads ___________________during breeding season • Gametes are shed into water (fertilization is external) • Pluteus larva spends several months in the plankton then undergoes metamorphosis to the adult

23. Class Holothuroidea (sea cucumber + in the form of) • 1,500 species found in all depths in all oceans • Crawl over hard substrates and burrow in soft substrates • Have _____________________ • Elongated along oral-aboral axis • Lie on one side so ventral is flat • Gives them a secondary bilateral symmetry • Have 3 – 5 rows of tube feet on this side (_____________________________________) • 2 rows on upper surface are reduced or absent • Tube feet around mouth are enlarged (referred to as “_________________________”)

24. Holothuroidea cont. • Body wall is thick and muscular, lacks protruding spines • Known as trepang in Asian countries • Eaten as a main course or added to soups for flavoring • Allows to move in wormlike wave along length of body • _______________ is internal • WVS is filled with coelomic fluid

25. HolothuroideaFunctions • Feeding = mucus covers tentacles to trap food • Digestion = stomach, long intestine, rectum, anus • Well developed hemal system • Excretion = ___________________________and anus via contractions and water flow through • Nervous system = similar to other echinoderms • Defense = defenseless against predators • __________________________________________________ • Some evert sticky, weblike tubules from respiratory tree through anus to tangle up predators….SEE IT IN ACTION

26. Holothuroidea Reproduction • Dioecious • Fertilization is _____________________ • On rare instances, eggs are released into the body cavity where fertilization and development occur. Then young leave through a rupture in the body wall. • Some use _______________________fission and then regeneration of lost parts

27. Class Crinoidea (___________+ in the form of) • Sea lilies and feather stars • Most _________of all echinoderms • Fyi…MO state fossil = __________. Why? • Approx. 630 living species today while many flourished during Paleozoic era 200 – 600 mya

28. Sea Lilies • Attach permanently to substrate by _________with a flattened disk or rootlike extensions • Disklike ossicles of stalk are attached by connective tissue • Unattached end is called the _______________ • Support between crown and stalk is _____________. Also where 5 arms attach. • Tube feet in double rows along each arm.

29. Feather Stars • Similar to sea lilies, except: • lack a stalk • can swim (by raising and lowering arms) • can crawl (by pulling with tips of arms) • Watch them in action…

30. Crinoidea Functions • Circulation – ___________________ – Excretion – similar to other Echinoderms • Feeding – _______________________(plankton gets trapped in arms by tube feet, cilia in ambulacral grooves take to mouth) • Nervous – lack a nerve ring • Reproduction – some dioecious, some monoecious • ___________________– males develop before females to ensure cross-fertilization • Some spawn in seawater • Can also regenerate lost parts

31. Overview of Echinoderms: • BBC – Planet Earth: • Watch several echinoderms living together • Dissection Tutorials: • Starfish dissection • Sea cucumber dissection • Articles: • Sea Urchins Tolerate Acid Waters