Sensory Perception

• Lateral line system - Eyes - fish often have excellent vision

• Otoliths in contact with hairlike fibers

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

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)

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

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

Location of ventral photophores on some deep-water fish

Mammals

Cetaceans: whales and porpoisesPinnipeds: seals, sea lions, walrusesMustelids: sea ottersSirenians: sea cows, dugongs

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

Whales and Porpoises

• All homeothermic

• Reproduce much the same as terrestrial mammals

• Posterior strongly muscular - propulsion by means of flukes

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

Odotocete Killer whale, Orcinus orca

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

Ventral furrows

Continuousram

feeding

Intermittentram

feeding

Mysticete feeding with baleen plates

Mysticetes: humpback whale breaching

Baleen plate of a beached finback whale

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

Australian sea lion Neophoca cinerea

Sea otter, Enhydra lutris

Sirenians

• Includes manatee, dugong, extinct Stellar Sea Cow

• Sluggish, herbivorous

• Live in inshore waters, estuaries

Florida manatee Trichechus manatus

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

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

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

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

Seabirds

(a) emperor penguin, (b) wandering albatross, (c) magnificentfrigate bird, and (d) black-backed gull

Emperor penguin, equipped with a Critter Cam

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

Shorebirds

1. Include sandpipers, plovers, other groups

2. Great dependence upon terrestrial sites, especially for feeding

3. Often migrate great distances between feeding and nesting areas

4. 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

Shorebirds

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

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

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

Sea Turtles

Green turtle, Chelonia mydas, resting on reef in Maui

The End