Download Phylum Echinodermata

Phylum Echinodermata
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Phylum Echinodermata
Phylum Echinodermata
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Defining Characteristics
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A complex series of fluid filled canals with numerous
flexible feeding and locomotory appendages
5 pointed radial symmetry in adult
Phylum Echinodermata
Echinoderms Skeleton
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Have an internal skeleton of
calcium carbonate
– Ossicles vary in size and
structure and are
manufactured by
specialized cells
Feeding biology?
Phylum Echinodermata
Water vascular system
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A separate coelom is
used with
interconnecting fluid
filled tubes and canals
A ring canal circles the
mouth and gives off 5
radial canals
The radial canal is
exposed and runs along
the ambulacral groove
Phylum Echinodermata
Water Vascular System
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Phylum Echinodermata
Tube Feet
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The ampullae is a
small ball that sits
above the tube foot
Contraction and
expansion of the
ampulla accomplishes
movement
Phylum Echinodermata
Mutable Connective Tissue
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Another unique Echinodermata
characteristic is the presence of mutable
connective tissue
Phylum Echinodermata
Taxonomic Summary
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Phylum Echinodermata
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Class Crinoidea
Class Concentricycloidea
Class Stelleroidea
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Subclass Asteroidea
Subclass Ophiuroidea
Class Echinoidea
Class Holothuroidea
Phylum Echinodermata
Subclass Asteroidea
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Phylum Echinodermata
Sea Stars
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The oral surface of each arm has a single ambulacral
groove
Have a large coelom where all the main organs occur
Phylum Echinodermata
Sea Star Feeding
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Feed mainly on slow
moving, sedentary,
or sessile
invertebrates
Some species evert
the stomach onto
prey and digest
externally, others
swallow whole
Phylum Echinodermata
Pedicellariae
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Specialized pinchers
found on the aboral
surface.
Phylum Echinodermata
Reproduction
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Can reproduce asexually
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by disk division
Sexual Reproduction
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Dioecious with sperm
or eggs produced in 2
or more gonads in
each arm
Larval stage =
bipinnaria
Phylum Echinodermata
Regeneration
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Many species autotomize,
leaving predators with a
nutritious souvenir while
they escape
Most spp. can regenerate
from fragments that
include the disk
Phylum Echinodermata
Subclass Ophiuroidea
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Defining Characteristics
– Well-developed
ossicles in the arms
forming a system of
articulating vertebrae
– The oral surface bears
5 pair of bursal sacs
Phylum Echinodermata
Brittle Star Structure
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Phylum Echinodermata
Reproduction
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Similar to Asteroids;
yet a pluteus larva
is formed
Regenerate well,
and one spp., in our
area reproduces
asexually by disk
division
Phylum Echinodermata
Class Echinoidea
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Defining characteristics
– Ossicles are joined to form
a rigid test
– Adults possess a feeding
structure called Aristotle’s
lantern
Two attributes: mobile spines,
and hollow skeleton or test
Phylum Echinodermata
Sea Urchin Structure
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Phylum Echinodermata
Pedicellariae
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Pedicellariae prevent
fouling of test and
are used in defense
More complex than
sea stars and are
located on tall
moveable stalks
Phylum Echinodermata
Ingestion and Digestion
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Feed on alga material, encrusting bryozoans or
scavenge
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Food is chopped by 5 sharp pointed teeth
The digestive system is long to deal with vegetable
manner
The anus is located aborally
Phylum Echinodermata
Reproduction
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Most conspicuous
organs are those
responsible for
reproduction
At spawning the entire
coelom will fill with
sperm or eggs
Pluteus larva is
formed
Phylum Echinodermata
Sand Dollars
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Irregular: nonspherical variously
depressed
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Anus is shifted to the
oral surface posterior
to the mouth creating
bilateral symmetry
Phylum Echinodermata
Class Holothuroidea
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Defining characteristics
– Worm shaped body, greatly elongated along the
aboral and oral axis
– The calcareous ossicles are reduced in size and
embedded individually in the body wall
– Highly branched muscular respiratory structures
Phylum Echinodermata
Holothuroidea Feeding
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Possess retractile
feeding tentacle that
surrounds the mouth
While suspension or
deposit feeding each
tentacle is cleaned in the
mouth
Phylum Echinodermata
Holothuroidea Structure
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Phylum Echinodermata
Ossicles
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Although somewhat
soft they do have an
internal skeleton
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The skeletal elements
(ossicles) are microscopic
with complex shapes
May compose up to 80%
of the dry body weight
Phylum Echinodermata
Respiration
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Respiratory trees
Phylum Echinodermata
Defense
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Many spp. have powerful toxins in the body
wall
Cuverian tubules
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Also eviscerates to avoid predation
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Sticky and toxic tentacles which are shot out the
anus
Internal organs regenerate after a period of time
Phylum Echinodermata