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Zoology – Chapter 16 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 5 Classes: _________________ sea stars _________________ brittle stars, basket stars _________________ sea urchins, sand dollars _________________ sea cucumbers _________________ sea lilies, feather stars 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 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 watervascular system and may help equalize pressure 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 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. Sea Star Feeding Feed on snails, bivalves, crustaceans, polychaetes, corals, and others (or hand fed scallops) Mouth short esophagus large stomach intestine rectal cecae Stomach = 2 parts short 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 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 = _____________) 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 Class Ophiuroidea (snake + tail + in the form of) _______________group of echinoderms Basket Star with over 2,000 species Long arms sharply off of central disk gives pentagonal shape _______________dermal banchiae and Brittle Star (aka–serpent star) pedicellariae Tube feet ______________________ and ampullae Madreporite on the oral surface WVS is _____________used for locomotion; skeleton modified to grasp 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. Watch a Brittle Star move… 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… 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 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 _____________________ 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 Echinoidea: Maintenance Functions Aristotle’s lantern 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 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 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 “_________________________”) 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 Holothuroidea Functions 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 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 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 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. 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… 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 Overview of Echinoderms: BBC – Planet Earth: Watch several echinoderms living together Dissection Tutorials: Starfish dissection Sea cucumber dissection Articles: Sea Urchins Tolerate Acid Waters