Download document

Justin Liu
Antony Santiago
Echinodermata
Period 6
Click to Select a Topic
Echinoderms
Holothuroidea
Excretion
Classes
Concentricycloidea
Response
Asteroidea
Body Plans
Movement
Ophiuroidea
Feeding and
Digestion
Reproduction
Echinoidea
Respiration
Works Cited
Crinoidea
Circulation
Home
General Characteristics of
Echinoderms
• 6000 species
• Pentamerous radial symmetry- the body can be
•
divided into five parts around a main axis
Water vascular system- a hydraulic network of
canals that run through the body, usually ending
in a series of tube feet
– The organism can control internal water pressure to
extend/contract tube feet for locomotion, food
collection, and respiration
General Characteristics of
Echinoderms cont.
• Internal skeleton covered with spines and skin
•
– Consists of multitudes of ossicles (small
calcareous plates) forming flexible joints
Some species of sea stars actually extend their
stomachs into their victims in order to digest
them
General Characteristics of
Echinoderms cont.
• A system of endoskeletal elements
composed of a calcareous meshwork
called the stereom
• Construction of ambulacra (a radial area
bearing tube feet) by the addition of new
plates adjacent to the terminal, or ocular,
plate that marks the ends of the radial
canals.
• A diffuse sub-epithelial nervous system
Classes
• There are six classes in the phylum
Echinodermata.
– Asteroidea
– Ophiuroidea
– Echinoidea
– Crinoidea
– Holothuroidea
– Concentricycloidea
Asteroidea (The Sea Stars)
http://www.biodiversityexplorer.org/mm/echinoderms/asteroidea/index.htm
Ophiuroidea (The Brittle Stars)
http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filo-equinodermata6.php
http://www.eol.org/pages/2037
http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filo-equinodermata-6.php
Echinoidea
(The Sea Urchins and Sand Dollars)
http://oceanlink.island.net/biodiversity/ask/echino.html
http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filo-equinodermata-5.php
Crinoidea
(The Sea Lilies and Feather Stars)
http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filoequinodermata-5.php
http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filo-equinodermata-5.php
Holothuroidea (Sea Cucumbers)
http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filo-equinodermata-6.php
Concentricycloidea (Sea Daisies)
http://www.mhhe.com/biosci/genbio/raven6b/grap
hics/raven06b/other/raven06_47.pdf
Body Plans
• Bilateral Symmetry [in larvae]-left and right
•
•
sides of an organism can be divided into mirror
images of each other
Radial Symmetry [in adults]-symmetrical
arrangement of parts of an organism around a
single main axis
All echinoderms exhibit secondary radial
symmetry, because they exhibit bilateral
symmetry during larval development, but exhibit
radial symmetry as adults.
Feeding and Digestion
• Echinoderms have a stomach and mouth
area
– Some echinoderms, such as sea cucumbers
have a mouth on the bottom side of their
body, and an anus on the front of their body.
• In some echinoderms the tube feet are
important sensory organs and assist in
directing food into the mouth once the
animal has captured it
Feeding and Digestion Cont.
• Some echinoderms are carnivorous and
scavenge the ocean floor.
• Others such as feather stars and sea
cucumbers are mainly filter feeders, and
catch food in ocean currents.
• Certain species, such as the sea star,
actually extend their stomach into an
unwary victim to digest it.
Respiration
• Poorly developed respiratory system
• Most echinoderms take in oxygen across
the skin through small fingerlike
extensions of the coelem (main body
cavity) called papulae.
• The papulae are covered with a thin layer
of skin and protrude through the body
wall to function as gills.
Circulation
• Echinoderms have a simple circulatory
system that pumps water through its
body.
– echinoderms have an open circulatory
system with cilia circulating the fluids
through each arm.
• The echinoderm’s coelom, or main body
cavity, connects with a complicated
system of tubes that helps to provide
circulation
Excretion
• Amoeboid cells, which are foreign to the
echinoderm, carry wastes out of the
coelomic fluid.
• Waste removal also occurs through small
fingerlike extensions of the coelem called
the papulae.
• The process of excretion in echinoderms
also makes use of the echinoderm’s water
vascular system.
Response
• Have a poorly developed nervous system
and lack a brain
• Echinoderms have a light sensitive organ
called a eyespot that can detect light and
its general direction, which allows the
echinoderm to move in response to light.
• In some echinoderms their skin cells may
be sensitive to certain chemicals given off
by prey or predators
Movement
• All echinoderms possess an internal skeleton
• In sea stars and brittle stars, the skeleton is made up of
•
small calcareous plates (ossicles) which form flexible
joints that can be used for movement.
An echinoderms tube feet work to enable movement
– Canals of small muscular tubes (water vascular
system) supplies water to the tube feet.
– As tube feet press against a moving object, water is
then withdrawn from the tube feet, which results in a
suction effect.
– When water returns to the canals the suction of the
tube feet is released.
– This type of movement is generally very slow.
Reproduction
• Echinoderms are classified as
deuterostomes
– In deuterostomes, the blastopore (the first
opening that appears in the embryo) becomes
the animal’s anus
– Deuterostomes exhibit indeterminate
development in which none of the daughter
cell’s have a predetermined function and
some daughter cells could even form a new
organism.
Reproduction cont.
• Some echinoderms are diecious,
meaning that there are separate
female and male individuals.
• The males and females discharge
their sperm and eggs, respectively,
into the water to be fertilized
• A female can release one hundred
million eggs at once
Reproduction cont.
• Echinoderms usually perform sexual
reproduction, while some species perform
asexual reproduction
• Sexual reproduction involves the external
fertilization of eggs by spermatozoa.
• Asexual Reproduction usually involves the
division of the body into two or more parts
(fission) and the reproduction of missing
body parts.
Works Cited
• Lambert, Phil. "Echinoderms of BC." UBC Department of
Geography. Web. 20 Apr. 2010.
•
•
•
<http://www.geog.ubc.ca/biodiversity/efauna/Echin
odermsofBC.html>.
Echinoderms. Web. 20 Apr. 2010.
<http://www.mcwdn.org/Animals/Starfish.html>.
Wonders of the Sea: Echinoderms. Oceanside Meadows
Innstitute for the Arts and Sciences. Web. 20 Apr.
2010.
<http://www.oceaninn.com/guides/echino.htm>.
Raven, Peter, George Johnson, Susan Singer, and
Jonathan Losos. "Echinoderms." Biology. Sixth ed.
McGraw-Hill Companies, 2001. 933-44. Print.
Thank You