1. Phylum Bryozoa “moss animals”
1st phyla we will talk about and what we will cover in the lab today is…

2. Bryozoa Characteristics
Triploblastic
Organ level of organization
Bilateral Symmetry
Eucoelomate
Protostome

3. Bryozoa Characteristics
Gas Exchange
no organs, simple diffusion
Circulatory System
no organs, coelomic fluid
Excretion
no organs, simple diffusion
Nervous system
nerve ring surrounding pharynx and nerves in tentacles (no sensory organs)

4. Bryozoa Characteristics
Skeletal system
most have a cuticle composed of chitin or calcium carbonate (zoecium)
zoecium

5. Bryozoa Characteristics
Digestive System
lophophore: a contractile ring of ciliated tentacles surrounding the mouth
complete digestive system
U-shaped with anus outside lophophore (ectoproct)
lophophore
mouth
anus

6. Bryozoa Characteristics
Reproduction
most are monoecious
most species brood their eggs externally or within special cavities in their bodies
freshwater species are capable of asexual reproduction using statoblasts (similar to gemmules)
statoblasts

7. Bryozoa Characteristics
Colonial
bryozoans are sessile and live in colonies (zoarium)
colonies can be encrusting (thin sheets) or stoloniferous (plant-like)
encrusting bryozoan
stoloniferous bryozoan

8. Bryozoa Characteristics
Colonial
all zooids within a colony are connected by pores in each individuals cuticle
some Bryozoans are polymorphic and contain defensive zooids called avicularia
pores
Used in defense and anti-fouling

9. Phylum Echinodermata “spiny skinned” animals
1st phyla we will talk about and what we will cover in the lab today is…

10. Echinodermata Characteristics
Triploblastic
Organ level of organization
Pentamerous Radial Symmetry
No head, no brain
Eucoelomate
Deuterostome

11. Protostome vs Deuterostome
blastopore becomes the anus
radial / indeterminate cleavage
regulative development
enterocoely
(Echinodermata, Chordata
blastopore becomes the mouth
spiral / determinate cleavage
mosaic development
schizocoely
(Annelida, Arthropoda, Mollusca, Bryozoa*)

12. Protostome Mouth Formation
Blastopore becomes the mouth and the anus forms secondarily
Future anus
blastopore
archenteron
(primitive gut)
mouth

13. Deuterostome Mouth Formation
Blastopore becomes the anus and the mouth forms secondarily
Future mouth
blastopore
archenteron
(primitive gut)
anus

14. Protostome: Spiral Cleavage
2 cells
4 cells
8 cells
Blastomeres divide at an oblique angle to one another, so that each lies in the furrow created by the cells beneath them

15. Deuterostome: Radial Cleavage
2 cells
4 cells
8 cells
Blastomeres divide in a symmetrical fashion, producing layers of cells directly on top of one another

16. Protostome: Mosaic Development
One blastomere is removed
Development is arrested
(or is defective)
4-cell stage

17. Deuterostome: Regulative Development
One blastomere is removed
Development continues
Development continues
4-cell stage
 each blastomere is capable of regulating its development even when separated from the others

18. Protostome: Schizocoely
blastocoel
mesodermal cells
developing coelom
split in mesoderm
ectoderm
endoderm
mesoderm

19. Deuterostome: Enterocoely
blastocoel
early mesodermal pouch
separation of pouches from gut
developing coelom
ectoderm
endoderm
mesoderm

20. Echinodermata Characteristics
Water Vascular System
A system of coelomic canals that functions in:
circulation, gas exchange, excretion, and locomotion.
stone canal
madreporite
ring canal
radial canal
tube feet

21. Echinodermata Characteristics
Water Vascular System
ampulla
podium
The structure of the tube foot

22. Echinodermata Characteristics
Dermal Endoskeleton
All echinoderms have a dermal endoskeleton that is composed of calcareous ossicles and is covered by epidermis.
The endoskeleton allows continuous growth and provides protection.
Fused to form a test
(e.g. sea urchins)
Articulating plates
(e.g. starfish)

23. Echinodermata Characteristics
Dermal Endoskeleton
In many echinoderms the skeleton bears spines or bumps that are used for defense.
Sea urchin
Spines on crown of thorns starfish

24. Echinodermata Characteristics
Dermal Endoskeleton
The epidermis covering the endoskeleton contains many specialized structures:
Dermal branchiae
(respiration)
Pedicellaria
(anti-fouling)

25. Echinodermata Characteristics
Reproduction
usually dioecious
usually external fertilization (eggs and sperm are shed into the water where fertilization occurs)
indirect development with the presence of a free-swimming, bilateral larval stage (some have direct development)
spawning sea urchins
bilateral larval stage

26. Echinodermata Characteristics
Reproduction
this bilaterally symmetrical larval form undergoes metamorphosis into an adult with radial pentamerous symmetry (with 5 or more radiating areas)
bilateral larval stage
radial pentamerous adult

27. Phylum Echinodermata Class Asteroidea Class Echinoidea
Class Ophiuroidea
Class Holothuroidea
Class Crinoidea

28. Echinoderm Radiation aboral region Asteroidea anus oral region
arms
anus
oral region
ambulacral region
1st phyla we will talk about and what we will cover in the lab today is…
Echinodea
fused ossicles
Ophiuroidea
no ambulacral region
no anus
Holothuroidea
secondarily bilateral
Crinoidea
on a stalk
feathery arms

29. Class Asteroidea the “sea stars”

30. Class Asteroidea star shaped with variable number of arms
ambulacral grooves open with tube feet on oral side
anus and madreporite on aboral side
tube feet usually have suckers
pedicellaria present

31. Class Asteroidea
aboral
oral

32. Class Echinoidea the“sea urchins”, “sand dollars”, “heart urchins”, “sea biscuits”…

33. Class Echinoidea globular or disc- shaped with no arms
ossicle plates are fused to form a compact skeleton called a “test”
ambulacral grooves closed
movable spines with interspersed tube feet
tube feet usually have suckers
anus and madreporite aboral
pedicellaria present
Aristotle’s lantern

34. where the spines attach
Class Echinoidea
aboral
aboral
where the spines attach
ambulacral region

35. Class Echinoidea Aristotle’s lantern - complex chewing mechanism
oral
Inside the animal
oral
aboral
oral
Aristotle’s lantern
- complex chewing mechanism
- 5 teeth are attached

36. Class Ophiuroidea “brittle stars” and “basket stars”

37. Class Ophiuroidea star shaped with arms around an obvious central disc
ambulacral grooves closed and covered by ossicles (no tube feet within them)
tube feet without suckers and are not used for locomotion
incomplete digestive system no anus
pedicellaria absent

38. Class Ophiuroidea
oral
aboral
Central disc

39. Class Ophiuroidea
day
Although they don’t have any eyes, some brittle stars have photosensitive “lenses” all over their body.
They can detect light/dark such as shadows and change color.
night

40. Class Holothuroidea the “sea cucumbers”

41. Class Holothuroidea cucumber-shaped with no arms secondarily bilateral
ambulacral grooves closed
microscopic ossicles are embedded in muscular body  soft body
tube feet with suckers and some are modified around the mouth as feeding tentacles
pedicellaria absent
respiratory tree for gas exchange

42. Class Holothuroidea ambulacral region with tube feet anus mouth
oral
aboral
anus
mouth
feeding tentacles (modified tube feet)

43. Class Holothuroidea
Many cucumbers have a “pearlfish” living inside them.
This skinny fish enters and leaves its host through the anus at night to feed.
It is unknown whether the pearlfish is a parasite that feeds on the internal organs of the sea cucumber or whether it leaves the sea cucumber unharmed.

44. Class Crinoidea the “sea lilies” and “feather stars”

45. Class Crinoidea flower-shaped arms bearing pinnules stalked
ciliated ambulacral grooves on oral surface with tentacle-like tube feet for food gathering
body disc and stalk contain ossicles
madreporite, spines, and pedicellaria absent

46. Class Crinoidea
oral
arm
pinnules
stalk
aboral

47. Regeneration
Most Echinoderms are capable of regenerating parts of their bodies when they are lost.
Regenerating arm

48. Regeneration
Some sea stars and brittle stars use regeneration as a way to reproduce asexually.
“comet” sea star
brittle star

49. Regeneration
Most sea cucumbers are able to expel their intestine out of their anus, and regenerate the lost structures.
This is done in defense and during times of the year when food supply is low.

50. Indeterminate Growth
Many Echinoderms can grow or shrink depending on resource availability.
Many do not seem to senesce, so unless they are killed by a disease or predator, it is unknown how long they can live…

51. How do Bryozoa and Echinodermata fit in?
Echinoidea
Ophiuroidea
Crinoidea
Asteroidea
Holothuroidea
Bryozoa
Mollusca
Nematoda
Rotifera
Arthropoda
Annelida
Platyhelminthes
Nemertea
Cnidaria
Porifera
unknown
common ancestor