Transcript The Echinoderms

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