Sensory Perception

1. Sensory Perception • Lateral line system - Eyes - fish often have excellent vision • Otoliths in contact with hairlike fibers

2. Schooling • Behaviorally based aggregation of fish • Most tightly schooling species have silvery sides, which would confuse predators • Schools sometimes in the form of “fish balls” • Behavior related to predation; fish leaving school are attacked successfully • Schooling may also reduce drag, save on energetic cost of swimming

3. Body temperature • Most fishes - temperature conformers • Tunas and relatives, some sharks, use countercurrent heat exchange to reduce heat loss - have elevated body temperature • Elevated body temperature allows higher metabolic rate, localized heating of nervous system in some species (e.g., swordfish)

5. Mesopelagic Fishes • Fish living 150-2000 m • Fish have well developed eyes, often large mouths for feeding on large prey • Many have ventral photophores, serves purpose of counterillumination - camouflage to blend in with low light from above

6. Chauliodus has specialized backbone to accommodate opening of large mouth to consume prey

7. Location of ventral photophores on some deep-water fish

8. Mammals Cetaceans: whales and porpoises Pinnipeds: seals, sea lions, walruses Mustelids: sea otters Sirenians: sea cows, dugongs

9. Whales and Porpoises • All belong to the Cetacea • Odontoceti toothed whales (e.g., sperm whale, porpoises) • Mysticeti baleen whales - feed by means of baleen, which strains macrozooplankton, megazooplankton

10. Whales and Porpoises • All homeothermic • Reproduce much the same as terrestrial mammals • Posterior strongly muscular - propulsion by means of flukes

11. Odontoceti • Toothed, usually good hunters, feed on squid, fish, small mammals • Good divers • Oral communication common • Many species have bulbous melon, filled with oil - function could be sound reception • Usually social, killer whales live in pods, maternally dominated

12. Odotocete Killer whale, Orcinus orca

13. Mysticeti • Adults have horny baleen plates, which strain zooplankton • Right whales are continuous ram feeders • Rorqual whales (e.g. Blue) are intermittent ram feeders, periodically squeeze water out of large mouth chamber

14. Continuous ram feeding Ventral furrows Intermittent ram feeding Mysticete feeding with baleen plates

15. Mysticetes: humpback whale breaching

16. Baleen plate of a beached finback whale

17. Other Marine Mammals • Pinnipeds include seals, sea lions, walruses - have hair but lack thick blubber of cetaceans • Sea otters belong to the otherwise terrestrial family Mustelidae

18. Australian sea lion Neophoca cinerea

19. Sea otter, Enhydra lutris

20. Sirenians • Includes manatee, dugong, extinct Stellar Sea Cow • Sluggish, herbivorous • Live in inshore waters, estuaries

21. Florida manatee Trichechus manatus

22. Diving by Marine Mammals • Must breathe at surface - no “bends” • Problem oxygen for long dives • Most have increased volume of arteries and veins • Have increased blood cell concentration • Can decrease heart beat rate and O2 consumption • Can restrict peripheral circulation and circulation to abdominal organs

23. Gas Bubble Problems • Upon ascent, gas bubbles may be released in blood stream as pressure decreases - The Bends • Not as bad a problem as you might think, because marine mammals don’t breathe air under pressure at depth, like human divers • Seals and whales can restrict circulation between the lungs and rest of circulatory system and have small lung capacity

24. Seabirds • Penguins - flightless, southern hemisphere, high latitude, divers, insulated by blubber and feathers, countercurrent heat exchange in circulation to wings and feet, colonial breeders • Petrels - great gliders, colonial breeders, often divers from air • Pelicans - generally tropical, heavy, diverse hunting from diving to underwater swimming • Gulls, auks, puffins - feed on fish, often very abundant

25. Seabirds • Often colonial breeders • Believed to be monogamous • Courtship involves elaborate displays • Crowded breeding sites, often with several species, protected from predators such as mammals • Feeding involves either diving or underwater swimming • Long-distance migration between nesting and feeding areas is common

26. Seabirds (a) emperor penguin, (b) wandering albatross, (c) magnificent frigate bird, and (d) black-backed gull

27. Emperor penguin, equipped with a Critter Cam

28. The yellow-nosed albatross Thalassarche chlororhynchos flies with minimal effort, owing to its extraordinarily long wings that permit it to soar on modest air drafts

29. Shorebirds Include sandpipers, plovers, other groups Great dependence upon terrestrial sites, especially for feeding Often migrate great distances between feeding and nesting areas Variety of feeding mechanisms, ranging from probing beaks into sediment to catching crustacea and other organisms in the surf to clipping bivalve adductors and scooping out bivalve flesh

30. Shorebirds

31. Shorebirds The American black oystercatcher Haematopus bachmani (west coast U.S.) is an effective predator on bivalve mollusks. Note its robust bill, used for severing adductor muscles

32. Sea Turtles • All nest on sandy beaches and migrate to feeding grounds; females return to beach where they hatched, usually repeatedly; several species shown to use earth magnetic field to navigate in migrations • Feeding of adults varies (e.g., green turtle consumes seagrasses and seaweeds, Kemp’s ridley eat bottom invertebrates, leatherbacks eat jellyfish • Leatherbacks distinct from other species, have temperature conservation mechanisms, including a countercurrent exchange heat retention

33. Sea Turtles (a) a leatherback Dermochelys coriacea hatchling turtle crawling toward the sea; (b) a female leatherback nesting at night on a beach on Isla Culebra, Puerto Rico

34. Sea Turtles Green turtle, Chelonia mydas, resting on reef in Maui

35. The End