1. Chapter 7- Part 2
Marine Biology

2. Phylum Mollusca
Mollusks

3. Greatest # of species
Body covered by mantle made of calcium carbonate
Bilateral symmetry
Foot used for locomotion
Radula used to feed

4. Gastropods:
Snails
Mostly eat algae from rocks- ex. Periwinkles

5. Continued……
Some snails such as mud snails are deposit feeders

6. Continued…….
Snails such as whelks can be carnivorous preying on clams, worms, or small fish

7. Continued……
Sea slugs are snails without shells. Often have noxious chemicals or nematocysts for protection

8. Bivalves:
Clams, mussels, oysters
Body enclosed in shell
Gills filter food and used for breathing
Mantle lines the inside of shell

9. Continued……
Clams use foot to burrow in sand- water enters and leaves shell through siphon

10. Continued…….
Mussels attach themselves by using byssal threads

11. Continued……
Oysters cement their left shell to a hard surface- often other oysters
Pearl oysters are the source of most valuable pearls.

13. How a pearl is made:
Particles merge in between mantle cavity and shell
Oyster secretes shiny layers of calcium carbonate to coat irritating particle

14. Oysters can be forced to make pearls by inserting an irritant in shell (cultured pearl)

15. Cephalopods:
Octopus, squid, cuttlefish
Good swimmer
Complex nervous system
No shell

16. Arms with suckers to capture prey
Eyes on side of head
Move by forcing water out of their siphon, or funnel

17. Octopus
8 arms (2 in to 9 ft in size)
bottom dwellers
Efficient hunters- crabs, lobsters, and shrimp
Radula scrapes away flesh

18. Some are toxic and their bite can paralyze
Live in crevices and even discarded bottles
Distract predators by spraying ink

22. Squid Better adapted for swimming Ten arms
Two of the arms are longer and wider for catching prey
Sizes range up to 66ft in the giant squid

25. Cuttlefish
Similar to squid except the body is flattened

26. Biology of Mollusks

27. Digestion: Separate mouth and anus
Radula can be modified from scraping or drilling through flesh
Amount and strength of digestive enzymes range depending on matter being digested

28. Circulatory system:
Most mollusks have a open circulatory system- blood flows out of vessels into open space
Cephalopods have a closed circulatory system-blood always remains in vessels

29. Nervous System: Most mollusks have a ganglia
Cephalopods have a more advanced brain, similar to humans
Intelligent and remarkable learners- some cuttlefish can even change colors

30. Reproduction: Usually separate sexes Some hermaphrodites
In bivalves and some snails-external fertilization
Cephalopods and most snails- internal fertilization

31. Cephalopods do not have larvae- young born from and egg
Cephalopods do not have larvae- young born from and egg. Mother usually dies after egg hatches due to lack of food while guarding egg.

32. Phylum Arthropoda
Arthropods

33. Barnacles, shrimp, lobster, crab, etc.
Segmented
Bilateral symmetry
Jointed appendages
Exoskeleton

34. Molt to grow-old skeleton discarded, animal takes in water to expand itself, grows a new skeleton

35. Crustaceans:
Called the insects of the sea
Gills
Appendages used to swim, crawl, feed, and mate
Two pair of antennae (sensory organs)

36. Copepods- planktonic, some parasitic
Small Crustaceans
Copepods- planktonic, some parasitic

37. Barnacles-filter feeders; live attached to surfaces

38. Beach hoppers (amphipods)-tail and head curve down, strong jumpers

39. Isopods- marine version of a roly-poly

40. Krill- shrimp-like, filter feeders, main food source for many whales, penguins, and fish

41. Large Crustaceans
Decapods- shrimp, lobster, crab (10 legs)
Commercial importance
5 pair of walking legs
First pair larger for obtaining food and in defense

42. Shrimps typically scavengers
Lobsters tend to be nocturnal (hide during day)- scavenge and catch prey
Crabs are scavengers as well
Female crab-U shaped abdomen for carrying eggs
Male- V shaped abdomen

43. Small teeth or ridges are found in stomach for grinding
Digestion:
Small teeth or ridges are found in stomach for grinding
Digestive glands help digest and absorb nutrients

44. Nervous System:
Small brain
Compound eyes- In decapods at the end of stalks
Body posture used for communication: mating, disputes, hunting, etc.

45. Reproduction: Mostly separate sexes
Males directly penetrate females to reproduce
Reproduction in decapods takes place directly after molting
Can store sperm

46. Phylum Echinodermata:
Echinoderms

47. Sea stars, sea urchins, sea cucumbers, etc.
Larvae –bilateral symmetry
Adults-radial symmetry
Lack a head

48. Oral surface/aboral surface
Water vascular system
Tube feet and ampullae’s are part of this system
Madreporite connects internal to the external

49. *Sea Stars
Tube feet (with suckers) found in ambulacral groove
Pedicellariae help keep surface clean
Eat bivalves, snails, barnacles, etc.

50. Tube feet lack suckers-feeding Organic matter, small animals
*Brittle Star
Long arms
Tube feet lack suckers-feeding
Organic matter, small animals

51. *Sea Urchins
Round, rigid, spines
5 ambulacral grooves with spines
grazers
Flat version with short spines- sand dollar

52. *Sea Cucumbers
Worm-like
No spines
Oral/aboral surfaces at each end
Tube feet modified and resemble tentacles- used to pick up food

53. Interesting defense methods:
~ discharge sticky substance through anus
~eviscerate internal organs

54. *Crinoids Better known as feather stars or sea lilies Deep waters
Attached to bottom

55. *Digestion:
Most extend stomach through mouth-digest food- and then pull stomach back in

56. *Nervous System:
No brain
Complex behaviors for the absence of a brain- camouflage, reposition itself if moved

57. *Reproduction: Separates sexes Sperm/egg shed directly into water
Spawn all at once to ensure fertilization
Asexual reproduction- if central disks is separated it can form into two new organisms (regeneration)