Class Asteroidea. Reproductive System, Regeneration, and Autonomy

Size: px

Start display at page:

Download "Class Asteroidea. Reproductive System, Regeneration, and Autonomy"

Job Walters
5 years ago
Views:

1 Copyright The McGraw-Hill Compaies, Ic. Permissio required for reproductio or display. Class Asteroidea Reproductive System, Regeeratio, ad Autoomy Sexes separate i most sexes Pair of goads i each iterradial space Fertilizatio is exteral Eggs ad sperm are shed ito the water i early summer Regeerate lost parts Cast off ijured arms ad regeerate ew oes A arm ca regeerate a ew sea star if at least oefifth of cetral disc is preset 22-15

Larva grows three adhesive arms ad a sucker at the aterior Now called a brachiolaria Brachiolaria attaches to

2 Copyright The McGraw-Hill Compaies, Ic. Permissio required for reproductio or display. Class Asteroidea Free-swimmig larva, bipiaria, has cilia arraged i bads Ciliated tracts become larval arms Larva grows three adhesive arms ad a sucker at the aterior Now called a brachiolaria Brachiolaria attaches to substrate ad udergoes metamorphosis ito a radial juveile Arms ad tube feet appear, aimal detaches from stalk ad becomes a youg sea star 22-16

distict from the cetral disc Lack pedicellariae or papulae Ambulacral groove is closed ad coated

has a colum of articulated ossicles called vertebrae Arms are moved i pairs for locomotio Five

3 Copyright The McGraw-Hill Compaies, Ic. Permissio required for reproductio or display. Form ad Fuctio Largest i umber of species Over 2000 species Arms of brittle stars are sleder ad distict from the cetral disc Lack pedicellariae or papulae Ambulacral groove is closed ad coated with ossicles Madreporite is o the oral surface Tube feet lack suckers ad ampullae Each joited arm has a colum of articulated ossicles called vertebrae Arms are moved i pairs for locomotio Five movable plates act as jaws ad surroud mouth No aus Ski is leathery ad surface cilia are mostly lackig Class Ophiuroidea 22-17

Class Echioidea Diversity Approximately 950 species of livig

symmetry Up-foldig brigs the ambulacral areas up to the area

radial symmetry ad log spies Sad dollars ad heart urchis

4 Copyright The McGraw-Hill Compaies, Ic. Permissio required for reproductio or display. Class Echioidea Diversity Approximately 950 species of livig echioids Sea urchis lack arms but their tests show five-part symmetry Up-foldig brigs the ambulacral areas up to the area of the aus Most sea urchis have a hemispherical shape with radial symmetry ad log spies Sad dollars ad heart urchis (irregular echioids) have become bilateral with short spies Echioids occur from itertidal regios to deep ocea 22-18

5 Copyright The McGraw-Hill Compaies, Ic. Permissio required for reproductio or display. Class Echioidea Form ad Fuctio Echioid test has movable, stiff spies Tube feet exted alog the 5 ambulacral rows Spies articulate o ball-ad-socket joits moved by small muscles at the bases Some species have pedicellariae with poiso glads that secrete a toxi that paralyzes small prey 5 covergig teeth 22-19

6 Copyright The McGraw-Hill Compaies, Ic. Permissio required for reproductio or display. Class Echioidea Aus, geital pores, ad madreporite are aboral Iside the test is Aristotle s later Complex set of chewig structures Ciliated sipho coects esophagus to itestie Food ca be cocetrated i the itestie Sea urchis are largely omivorous But primary diet cosists maily of algae Sad dollars filter particles through spies 22-20

7 Copyright The McGraw-Hill Compaies, Ic. Permissio required for reproductio or display. Class Holothuroidea Diversity Approximately 1150 species of holothuroids As commo ame suggests, these aimals resemble cucumbers Greatly elogated i the oral-aboral axis Ossicles are greatly reduced ad body is soft/leathery Some species crawl o the ocea bottom, others are foud uder rocks or burrow 22-21

There may be three ambulacra All tube feet, except oral tetacles, are abset i burrowig forms Oral tetacles are 10 30 tube feet surroudig

8 Copyright The McGraw-Hill Compaies, Ic. Permissio required for reproductio or display. Class Holothuroidea Form ad Fuctio Most have tube feet oly o the ambulacra that faces the substratum (the sole). There may be three ambulacra All tube feet, except oral tetacles, are abset i burrowig forms Oral tetacles are tube feet surroudig the mouth Digestive system opes ito a cloaca Respiratory tree also empties ito cloaca Madreporite lies free i the coelom Respiratory tree also serves for excretio Gas exchage also occurs through the ski ad tube feet 22-22

Class Holothuroidea Sea cucumbers use vetral tube feet ad muscular

graze sea bottom with tetacles Cast out part of viscera whe irritated

9 Copyright The McGraw-Hill Compaies, Ic. Permissio required for reproductio or display. Class Holothuroidea Sea cucumbers use vetral tube feet ad muscular body waves to move Some trap particles o the mucus of tetacles Others graze sea bottom with tetacles Cast out part of viscera whe irritated Must regeerate these tissues Oe small fish, Carapus, uses the cloaca ad respiratory tree of a sea cucumber for shelter 22-23

CHAPTER 22. Echinoderms 22-1

CHAPTER 22. Echinoderms 22-1 CHAPTER 22 Echinoderms 22-1 Phylum Echinodermata: Diversity and Characteristics Characteristics All members have a calcareous skeleton Spiny endoskeleton consists of plates Unique water-vascular system