1. Echinoderms are defined by their radial symmetry as adults and possession of a water vascular system used for locomotion and feeding. They have an endoskeleton of calcium carbonate ossicles. 2. The phylum contains five classes: Asteroidea (sea stars), Ophiuroidea (brittle stars), Echinoidea (sea urchins and sand dollars), Holothuroidea (sea cucumbers), and Crinoidea (sea lilies). 3. Reproduction is both sexual, with external fertilization producing planktonic larvae, and asexual, with some species able to regenerate or divide their discs to reproduce.

1. Phylum Echinodermata1
Phylum Echinodermata

2. Phylum Echinodermata2
Phylum Echinodermata
 Defining Characteristics
– A complex series of fluid filled canals with numerous
flexible feeding and locomotory appendages
– 5 pointed radial symmetry in adult

3. Phylum Echinodermata3
Echinoderms Skeleton
 Have an internal skeleton of
calcium carbonate
– Ossicles vary in size and
structure and are
manufactured by
specialized cells
 Feeding biology?

4. Phylum Echinodermata4
Water vascular system
 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

5. Phylum Echinodermata5
Water Vascular System

6. Phylum Echinodermata6
Tube Feet
 The ampullae is a
small ball that sits
above the tube foot
 Contraction and
expansion of the
ampulla accomplishes
movement

7. Phylum Echinodermata7
Mutable Connective Tissue
Another unique Echinodermata
characteristic is the presence of mutable
connective tissue

8. Phylum Echinodermata8
Taxonomic Summary
 Phylum
Echinodermata
– Class Crinoidea
– Class
Concentricycloidea
– Class Stelleroidea
 Subclass Asteroidea
 Subclass Ophiuroidea
– Class Echinoidea
– Class Holothuroidea

9. Phylum Echinodermata9
Subclass Asteroidea

10. Phylum Echinodermata10
Sea Stars
 The oral surface of each arm has a single ambulacral
groove
 Have a large coelom where all the main organs occur

11. Phylum Echinodermata11
Sea Star Feeding
 Feed mainly on slow
moving, sedentary,
or sessile
invertebrates
 Some species evert
the stomach onto
prey and digest
externally, others
swallow whole

12. Phylum Echinodermata12
Pedicellariae
 Specialized pinchers
found on the aboral
surface.

13. Phylum Echinodermata13
Reproduction
 Can reproduce asexually
by disk division
 Sexual Reproduction
– Dioecious with sperm
or eggs produced in 2
or more gonads in
each arm
– Larval stage =
bipinnaria

14. Phylum Echinodermata14
Regeneration
 Many species autotomize,
leaving predators with a
nutritious souvenir while
they escape
 Most spp. can regenerate
from fragments that
include the disk

15. Phylum Echinodermata15
Subclass Ophiuroidea
 Defining Characteristics
– Well-developed
ossicles in the arms
forming a system of
articulating vertebrae
– The oral surface bears
5 pair of bursal sacs

16. Phylum Echinodermata16
Brittle Star Structure

17. Phylum Echinodermata17
Reproduction
 Similar to Asteroids;
yet a pluteus larva
is formed
 Regenerate well,
and one spp., in our
area reproduces
asexually by disk
division

18. Phylum Echinodermata18
Class Echinoidea
 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

19. Phylum Echinodermata19
Sea Urchin Structure

20. Phylum Echinodermata20
Pedicellariae
 Pedicellariae prevent
fouling of test and
are used in defense
 More complex than
sea stars and are
located on tall
moveable stalks

21. Phylum Echinodermata21
Ingestion and Digestion
 Feed on alga material, encrusting bryozoans or
scavenge
– Food is chopped by 5 sharp pointed teeth
– The digestive system is long to deal with vegetable
manner
– The anus is located aborally

22. Phylum Echinodermata22
Reproduction
 Most conspicuous
organs are those
responsible for
reproduction
 At spawning the entire
coelom will fill with
sperm or eggs
 Pluteus larva is
formed

23. Phylum Echinodermata23
Sand Dollars
 Irregular: non-
spherical variously
depressed
– Anus is shifted to the
oral surface posterior
to the mouth creating
bilateral symmetry

24. Phylum Echinodermata24
Class Holothuroidea
 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

25. Phylum Echinodermata25
Holothuroidea Feeding
 Possess retractile
feeding tentacle that
surrounds the mouth
 While suspension or
deposit feeding each
tentacle is cleaned in the
mouth

26. Phylum Echinodermata26
Holothuroidea Structure

27. Phylum Echinodermata27
Ossicles
 Although somewhat
soft they do have an
internal skeleton
– The skeletal elements
(ossicles) are microscopic
with complex shapes
– May compose up to 80%
of the dry body weight

28. Phylum Echinodermata28
Respiration
 Respiratory trees

29. Phylum Echinodermata29
Defense
 Many spp. have powerful toxins in the body
wall
 Cuverian tubules
– Sticky and toxic tentacles which are shot out the
anus
 Also eviscerates to avoid predation
– Internal organs regenerate after a period of time