Phylum Echinodermata

1. Phylum Echinodermata

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Phylum Echinodermata

2. Phylum Echinodermata

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

3. 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

4. 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

5. Water Vascular System

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Phylum Echinodermata

6. 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

7. Mutable Connective Tissue

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Another unique Echinodermata
characteristic is the presence of mutable
connective tissue
Phylum Echinodermata

8. Taxonomic Summary

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

9. Subclass Asteroidea

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Phylum Echinodermata

10. 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

11. 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

12. Pedicellariae

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Specialized pinchers
found on the aboral
surface.
Phylum Echinodermata

13. Reproduction

Can reproduce asexually
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

14. 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

15. 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

16. Brittle Star Structure

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Phylum Echinodermata

17. 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

18. 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

19. Sea Urchin Structure

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Phylum Echinodermata

20. 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

21. Ingestion and Digestion

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

22. 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

23. Sand Dollars

Irregular: nonspherical variously
depressed
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Anus is shifted to the
oral surface posterior
to the mouth creating
bilateral symmetry
Phylum Echinodermata

24. 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

25. 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

26. Holothuroidea Structure

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Phylum Echinodermata

27. Ossicles

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

28. Respiration

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Respiratory trees
Phylum Echinodermata

29. Defense

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