Remaining Nekton

Mammals

  • Cetaceans: Whales and Porpoises (Odontoceti are Toothed whales aka sperm whale or porpoise and Mysticeti are baleen whales)

  • Pinnipeds: Seals, sea lions, walruses

  • Mustelids: Sea otters

  • Sirenians: Sea cows, dugongs aka manatees

General characteristics

  • Homeotherms

  • Reproduce similar to terrestrial mammals (K-selected?)

  • Propelled by flukes (rear tail)

Odontoceti

  • Toothed, great hunters and divers. Feed on squid, fish, and small mammals

  • Oral communication

  • Social … Matriarchal society

  • Often have a bulbous melon filled with oil, maybe for sound reception?

  • Weird guy: Hector’s Dolphin. Lives in New Zealand and is very small.

Mysticeti

  • Adults have baleen plates which strain zooplankton

  • Right whales are continuous ram feeders (have their mouths open all the time)

  • Rorqual whales are intermittent ram feeders, periodically squeeze water out (only open their mouths sometimes, gulps)

  • Breaching (jumping out of the water), collaborative feeding, bubble nets (used to catch prey) are notable behaviors

Pinnipeds

  • Seals, sea lions, elephant seals, and walruses

  • Hair and some blubber

  • Land birth

  • Breeding on coast or ice offshore (harems in walruses and sea lions)

  • Seals vs sea lions: They have little ear flaps. Seals have no external ears. Sea lions have very long front flippers that regulate body temperature. Seals have short front flippers. Sea lions have rear flippers to walk on but seals cannot. Sea lions are skinnier and seals are fatter. Sea lions use fore flippers to propel in the water while seals use their rear flippers. Both are social and playful.

Sea otters

  • Mustelid

  • Streamlined body

  • Modified appendages - webbed feet

  • Prey on benthic species

  • Fur as thermal barrier

  • Important in structuring kelp barrier - Keystone Species

  • Mate in water and are territorial

  • Densest fur out of all the animals

Sirenians

  • Manatee, dugongs, extinct stellar sea cow

  • Sluggish and herbivorous

  • Live in inshore waters and estuaries

Diving challenges: Must breathe at surface. Strategies → volume of arteries and veins are increased, increased blood cell counts, decreased heart rate, storage of O2 attached to hemoglobin in muscles, restrict peripheral circulation/circulation to abdominal organs

Gas bubble problems: The Bends - Release of mostly nitrogen gas into blood stream - very painful!! Marine animals don’t breathe air under pressure at depth, they just hold their breath.

  • Pressure increases with depth

Seabirds

Colonial breeders, territorial for good nesting sites

Monogamous

Crowded breeding sites, often with several species

Feeding varies, some dive and some swim

Long-distance migration between nesting and feeding is common

Clumsy on land

Penguins

  • Flightless, southern hemisphere, divers, blubber, retaining heat, colonial breeders

Pertrels and Albatrosses

  • Gliders, large wingspan, can be over 50 y/o, colonial breeders, dive from the air

Pelicans and co.

  • Generally tropical, heavy, diverse hunting, can maneuver well

Gulls, auks, and puffins

  • Very diverse, feed on fish, often very abundant

Albatross specifics

  • Can be over 60 y/o, largest wingspan, spends over 80 percent of life at sea, pair for life. Flight speed up to 100km/h, breed for 75 days, take turns feeding a baby, chick fledging might take up to 280 days - Rime of the Ancient Mariner !!!!!!

Shorebirds

  • Sandpipers, plovers, others

  • Great dependence on terrestrial sites, especially for feeding

  • Often migrate great distances between feeding and nesting areas

  • Variety of feeding mechanisms - very different beak shapes

  • Several have webbed feet, helps them not get stuck in the sand or mud

Sea Turtles

Nest on sandy beaches and migrate to feeding grounds (offspring gender depends on sand temperature)

Females return to beach where they hatched, usually repeatedly (maybe they use Earth’s magnetic field to orient themselves in the ocean?)

Lachrymal gland regulates salt content

Can forage underwater for nearly an hour, can sleep underwater for 7 hours or so

Sea turtles

  • Green, Loggerhead, Kemp’s Ridley, Olive Ridley, Hawksbill, Flatback, and Leatherback

  • Feeding varies, green turtles eat seagrasses and seaweeds while Kemp’s Ridley eats benthic invertebrates and Leatherbacks eat jellyfish, Hawksbills eat sponges

  • Leatherbacks are Only Endothermic !!! Have temperature conservation mechanisms - countercurrent exchange to retain heat

  • Require a long time to reach reproductive age - around 10 years

  • Biofluorescence - glow under light