1. Phylum Cnidaria

2. Phylum Cnidaria Examples: Sea anemones Corals Sea Pen Sea Fan
Sea Plume
Hydra
Jelly fish
Portuguese Man o’ War
Box Jelly Fish

3. Cnidaria (nettle like or connected with) relatively simple animals
Level of Organization:
cells & tissue
No true organs
most are sessile,
those that are unattached (such as jellyfish) can swim only feebly
More than 9000 species

4. Cnidaria Mostly found in shallow marine habitats,
especially in warm temperatures and tropical regions
few in fresh water
Little economic importance
Neurotoxins in medical research
Coral – jewelry, building, reefs
Coral reefs
habitat for many
great biodiversity
protect coastline
Symbiosis with other organisms

5. Phylum Cnidaria
Phylum includes branching, plantlike hydroids; flowerlike sea anemones; jellyfishes; gorgonian corals; stony corals
Symbiotic relationships
Algae frequently live in a mutualistic relationship in the tissues of cnidarians
Fish living within tentacles of a
Portuguese man of war
Sea anemone & clown fish

6. Phylum Cnidaria Four classes of Cnidaria: Hydrozoa – Scyphozoa Cubozoa
the most variable class including hydroids, fire corals, Portuguese man-of- war, and others
Scyphozoa
“true” jellyfishes
Cubozoa
cube jellyfishes
Anthozoa
the largest class; includes sea anemones, stony corals, and others

7. Form and Function
All cnidarian forms fit into one of two morphological types (dimorphism): a polyp or a medusa
Polyp – a hydroid form which is adapted to a sedentary or sessile life
Medusa – a jellyfish form which is adapted for a floating or free- swimming existence

8. Form and Function Polyp – Most have tubular bodies
A mouth surrounded by tentacles defines the oral end of the body
Mouth leads into a blind gut or gastrovascular cavity
Aboral end of the polyp is usually attached to a substratum by a pedal disc or other device

9. Form and Function Medusae – usually free swimming
bell-shaped or umbrella-shaped bodies
tetramerous symmetry
body parts arranged in fours
Mouth is usually centered on the concave side
Tentacles extend form the rim of the umbrella
Are essentially an unattached polyp with the tubular portion widening and flattening into the bell shape

10. Body Wall body wall surrounding the gastrovascular cavity consists of:
an outer epidermis
an inner gastrodermis
with mesoglea between them
Cnidocytes are found throughout the epidermis

11. Cnidocytes
Explosive cell containing one giant secretory organelle or cnida
(plural cnidae)
Used for prey capture and defense from predators.
A cnidocyte fires a structure that contains the toxin, from a characteristic sub-cellular organelle called a cnidocyst
(also known as a cnida or nematocyst).
This is responsible for the stings delivered by jellyfish

12. Cnidocytes They have three functions
Penetrate prey and inject poison
Recoil and entangle prey
Secrete an adhesive substance used in locomotion and attachment (glutinants)
Note = most are not harmful to humans, however Portuguese man-of-war and certain jellyfish are quite painful and sometimes dangerous

14. Cnidocytes

16. Locomotion
Hydras can move about freely by gliding on their basal disc, aided by mucus secretions
They can also use a “measuring worm” movement, looping along a surface by bending over and attaching their tentacles to the substratum
Medusae – can move freely and swim by contracting the bell, expelling water from the concave, oral side

17. Reproduction
Polyps
Budding – a knob of tissue forms on the side of an existing polyp and develops a functional mouth and tentacles
Bud that detaches from the polyp is a clone
When buds do not detach, a colony forms and food may be shared through a common gastrovascular cavity

18. Reproduction Fission Pedal Laceration Polyp continued –
one-half of a polyp pulls away from the other
Pedal Laceration
tissue torn from the pedal disc develops into new, tiny polyps

19. Reproduction Sexual Medusae release sperm & eggs
Some monoecious, some dioecious
Monoecious = “one house”
Dioecious = “two houses” (separate sexes)
Larvae free-swimming

20. Life Cycles
polyps and medusae play different roles
in general a zygote develops into a free-swimming planula larva
the planula settles and metamorphoses into a polyp
a polyp makes other polyps asexually,
polyps in Hydrozoa and Scyphozoa eventually make medusae
Medusae (made asexually) develop into either male or female individuals and produce gametes
Fertilization typically occurs in open water

22. Feeding and Digestion the mouth opens into the gastrovascular cavity
digestion is started in the gastrovascular cavity (extracellular digestion) by enzymes discharged by gland cells
nutritive-muscular cells phagocytize many food particles for intercellular digestion

23. Class Hydrozoa most are marine and colonial in form
found throughout the world, with 16 species occurring in North America
Hydra
(freshwater – normal habitat is underside of aquatic leaves and lily pads in cool, clean fresh water of pools and streams)

24. Portuguese man-of-war

25. Portuguese man-of-war

26. Portuguese man-of-war attack

27. Class Scyphozoa includes most of the larger jellyfish (cup animals)
most range from 2 to 40 cm in diameter (may attain a bell over 2 m in diameter and tentacles 60 to 70 m long)
the bell can vary from a shallow saucer to a deep helmet of goblet shape
range in color from colorless to bright orange and pink

28. Giant jellyfish

29. Giant Jellyfish

30. Northern Sea Nettle
common in near surface waters off the West Coast of the USA, as well as from Japan to the Bering Sea

31. Darwin’s Jellyfish
..\Animals\Darwin's Jellyfish\Darwin’s Jellyfish.ppt

32. Class Cubozoa bells are almost square
a tentacle or group of tentacles if found at each corner of the square at the umbrella margin
strong swimmers and fierce predators, feeding mostly on fish

33. Carybdea

34. Carybdea

35. C. fleckeri

36. C. fleckeri

37. Box Jelly or Sea Wasp (lethal)

38. Box Jelly Video

39. Sting of a Sea Wasp
The venom has cardiotoxic, neurotoxic and highly dermatonecrotic components

40. Class Anthozoa “flower animals” No medusa stage
Found in both shallow and deep water, polar as well as tropical seas
There are three subclasses
Zoantharia (sea anemones, hard corals, and others)
Ceriantipatharia (tube anemones, thorny corals)
Octocorallia (sea fans, sea pens, sea pansies)

41. Zoantharia – sea anomone

42. Zoantharia – sea anomone

43. Zoantharia – coral reef

44. A Closer Look at Coral

45. Ceriantipatharia – Tube anemone

46. Ceriantipatharia – Tube anemone

47. Ceriantipatharia – Tube anemone

48. Octocorallia – sea pens

49. Octocorallia – sea pens

50. Octocorallia – sea pens

51. Ctenophores phylum contains fewer than 100 species
all are marine in all seas, but most especially in warm waters
they take their names from eight rows of comblike plates used for locomotion
common names are “sea walnuts” and “comb jellies”
most are free-swimming and are common in surface waters
the fragile, transparent bodies are easily seen at night when they emit light (luminescent)

52. Comb jellies

53. Comb jelly

54. Comb jelly

55. Beroe cucumis

56. Beroe

57. Comb jelly