Marine Mammals Picture: G. Bearzi

WHO ARE THEY? Photo: web

Marine mammals Land-dwelling ancestors Warm-blooded Breathe air Hair/fur Bear live young Mammary glands for milk They all have 3 ear bones.

Three Categories of Marine Mammals Cetacea (se-tay-she-ah) whales, dolphins, and porpoises Carnivora polar bears, otters, seals, sea lions, walruses Sirenia (sire-een-e-uh) manatees and dugongs Photo: web

CETACEA: Toothed whales Photo: M. Bearzi ©2000

Bottlenose dolphin Striped dolphin Images: M. Demma Common dolphin

Rough-toothed dolphin Globicephalo... Risso’s dolphin Killer whale Focena comune False killer whale Images: M. Demma Rough-toothed dolphin Globicephalo...

Risso’s dolphin Pilot whale Images: M. Demma Harbor porpoise

Cuvier’s beaked whale Images: M. Demma Sperm whale...

SPERM WHALE

Not much of a species barrier!

CETACEA: Baleen whales Photo: web

Fin whale Right whale Images: M. Demma Sei whale Humpback whale

Cetacea Adaptations for deep diving Use oxygen efficiently Absorb 90% of oxygen inhaled (lots of capillaries) Store large quantities of oxygen (lots of hemoglobin) Reduce oxygen required for noncritical organs Dive 10 min (dolphin) to 2 hours (Sperm Whale) Muscles insensitive to buildup of carbon dioxide Collapsible lungs

Temperature Regulation Blubber (also for buoyancy and energy storage) Counter-current blood flow – warms blood as it returns to core of body Muscles generate heat Low surface area to volume ratio - little surface in contact with water to lose heat

Oxygen blowhole (nostrils) on head – easier Empty and fill lungs quickly (2 seconds for a fin whale) Large lungs High gas exchange rate (absorb 90% of oxygen - humans absorb 20%)

Oxygen Many red blood cells, hemoglobin – carries oxygen myoglobin - carries additional oxygen Shunt blood from non-vital organs (stomach, kidney) when diving to vital organs (brain, heart, muscles) Slow heartbeat rate when diving

Propulsion Through the Water Streamlined Internalized body parts - ear, penis, mammary glands – reduces friction Shorter appendages – forelimbs for steering Loss of hind limbs Loss of hair

Propulsion Through the Water fluke (tail) for propulsion Up and down (unlike fish = side to side) ↑ surface area Also to identify individuals - like fingerprint flippers – for steering and balance

Sensing the Environment Good eyesight – but little to no light echolocation - biological SONAR – find and maybe to stun prey Very good hearing - sound travels faster in water than in air ex: humpback songs for communication – social, territorial

Communication whistles Echolocation clicks Cetaceans’ sensory world SOUND Communication whistles Echolocation clicks Photo: web

Cetaceans’ sensory world Song of a whale Photo: web Dolphin whistles

Types of Whales Toothed whales – suborder Odontoceti Baleen whales – suborder Mysticeti

Types of Whales – Toothed Whales Have teeth – to catch prey, not chew Eat mostly fish and squid - killer whales eat seals Dive deeper Most do not migrate Ex: sperm, pilot, killer whales, dolphins, porpoises Ex: sperm whales dive > 3,500 feet for giant squid, up to 75 minutes

Types of Whales – Baleen Whales No teeth - 600 - 800 baleen plates to filter krill and other items ex: blue whale eats 4 tons of krill per day Not deep divers ex: humpback - lung feeding (lunge forward, pleats open), flick feeding (flick tail), bubble feeding (blow bubble net and swim up)

Types of Whales – Baleen Whales pleats – folds under mouth open like accordion when feeding

baleen ventral grooves jaw tongue Image: from M. Jahoda book, modified

Feeding Image: G. Bearzi Other whales

Types of Whales – Baleen Whales ex: humpback - lunge feeding (lunge forward, pleats open), flick feeding (flick tail), bubble feeding (blow bubble net and swim up)

Types of Whales – Baleen Whales ex: blue, humpback, right, gray, fin North to feed, south to breed - behavioral adaptation north - summer for krill south - winter to raise young ex: gray whales, 3 month migration, Arctic to Baja, CA, 6,000 mi one way

Order Carnivora Pinnipeds (large skin covered flippers) Walruses Seals Sea lions Fur seals

CARNIVORA: Pinnipeds Otariidae sea lions, fur seals, etc Phocidae true seals Photos: M. Bearzi ©2000

Family Phocidea (Pho-ce-die) “True or Earless Seals” No external ears Flippers covered in fur Hind flippers cannot be turned forward under the body for use in terrestrial motion Moves on land by wiggling like a catapillar

Family Otariidae (ota-rye-uh-dee) “Eared Seals” Sea Lions and Fur Seals Visible external ears Flippers are hairless Hind flippers can be placed under body for awkward locomotion Longer front flippers

Sea Lion vs. Seal

Figure 9.09b

Odobenidae (Odo-ben-i-de) walruses CARNIVORA: Pinnipeds Odobenidae (Odo-ben-i-de) walruses Photo: web

CARNIVORA: Ursidae polar bears Photo: web

sea otters, weasels, minks, etc CARNIVORA: Mustelidae sea otters, weasels, minks, etc Photo: web

dugongs, Stellar’s sea cows SIRENIA: Trichechidae manatees Dugongidae dugongs, Stellar’s sea cows Photos: web

Order Sirenia Includes Manatees and Dugongs “Sea Cows” Closely related to elephants Named after sirens from Greek mythology. (mermaids)

Sirenians Move by moving tail up and down Well-padded with blubber A few scattered hairs

Sirenians: only eat seagrasses and other aquatic vegetation extremely low metabolism zero tolerance for cold water. 

Sirenians are restricted to warm shallow coastal waters, estuaries, and rivers, with healthy ecosystems that support large amounts of seagrass and/or other vegetation.

A byproduct of their diet is that Sirenians produce a large volume of gas, which is given off during the digestion of plant material and this makes them particularly buoyant, so much so that their bones are dense in order to compensate

SIRENIA: Four living species placed in two families make up this order Compare that to: ~78 species of cetaceans ~235 species of primates SIRENIA:

Amazonian manatee

African manatee

West Indian manatee

Dugong

Thought that the species was likely extinct by 1768. Extinct Steller’s Sea Cow Thought that the species was likely extinct by 1768.

Hydrodamalis was hunted primarily as a source of food Hydrodamalis was hunted primarily as a source of food. Steller (1751) describes the meat as being easily prepared and similar to beef in taste and texture. The blubber was useful for: cooking lamp oil. The milk of harvested cows was consumed directly or made into butter. The thick, tough hide was used for shoes, belts and to make skin-covered boats.

Once known to occur in large herds and have healthy populations , the Amazonian manatee has suffered from extensive hunting by subsistence and commercial hunters

Other Threats: The deforestation of large areas of the forests surrounding this manatee’s river habitats has also caused soil erosion, degradation of food supplies and the reduction of vegetation in the waterway

Meanwhile in Florida….. Watercraft collisions account for approximately 25% of all manatee deaths

http://live.wsj.com/video/mellow-manatees-at-the-center-of-a-storm/001901E5-5BC5-4544-8D2B-C17A9D74119B.html#!001901E5-5BC5-4544-8D2B-C17A9D74119B

Anderson (1995) has also noted that the intense hunting of sea otters on the Bering Sea islands may have contributed to the final extinction of Hydrodamalis. It is known that sea urchin populations can severely deplete sea grass and algae communities when otters are removed, and as this happened on the Bering Sea islands, the sea cows would have faced a new competitor for food. A similar course of events may have occurred 12,000-14,000 years earlier along the coast of Asia and North America as aboriginal peoples colonized the areas and began hunting otters and sea cows (Anderson, 1995).