Marine Biology: Marine Mammals

What are the organisms of the cetaceans?

Whales, dolphins, porpoises. Suborder: Odontoceti (toothed whales). Suborder: Mysticeti (baleen whales)

What are the organisms of the pinnipeds?

Seals, sea lions and walruses

What are the organisms of the mustelids?

Sea otters

What are the organisms of the sirenians?

Sea cows and dugongs

What are the major morphological characteristics of cetaceans?

-hairless and streamlined body to reduce drag

-modified forelimbs into stabilizing paddles. hind limbs completely lost and only identified by vestigial bones

-posterior strongly muscularized, ends in pair of flukes

How are cetaceans homeothermic?

They have a thick subdermal layer of fat that slows heat loss where in extreme cold blood circulation is restricted to vital organs. Heat conserved in limbs by countercurrent heat exchange

How do cetaceans reproduce?

Elaborate courtship rituals with a gestation period (blue whale 1 year and killer whale 16-17 months). Young is born underwater and young are typically large. Cared for by mothers for 2 years

Why do cetaceans have to return to surface for oxygen?

Because they are air breathers

Where is the nasal opening in cetaceans?

Located as the blowhole on the back dorsal surface of the head

What happens when the whale reaches the surface to breathe?

There is a characteristic loud sneezing sound as CO2 is expelled through special flaps that seal off nasal opening when animal dives

What are the 2 suborders of cetaceans?

Odontoceti and mysticeti

What are the species of the odontoceti?

They are the toothed whales which include sperm whales, killer whales, beluga whales and porpoises

What is the diet of odontoceti?

They eat large prey such as fishes, smaller marine mammals (seals and otters)

Do odontoceti have typical mammalian teeth?

Yes and they are modified to various degrees

Why do odontoceti have a singular blowhole?

Because they are excellent divers; this is related to their hunting behavior for mobile prey

How is the echolocation sound produced in odontoceti?

Focused through melon (bulbous structure on upper skull) which focuses reception and transmission of sound waves

Why is echolocation important in odontoceti?

Important for communication and social interaction, where travelling in small pods is the rule

What are the species of the mysticeti?

Baleen whales including blue whales, humpback whales, gray whales

What are baleen plates made of?

Made of keratin and derived from dermal tissue

Where are baleen plates attached to?

Attached to margin of the upper jaw; each composed of tightly packed fibers that are frayed on the edge facing the inside of the mouth

Do baleen plates strain water?

Yes, since they strain water the prey in the water is able to remain in the mouth

Do all mysticetes have 2 blowholes?

Yes

What are the 2 major groups of Mysticeti?

The right whales and the rorqual whales

What are the right whales?

Part of Mysticeti, bowheads, which are continuous ram suspension feeders. Longer baleen plates and swim relatively slow through water continuously straining water for zooplankton

What are the rorqual whales?

Part of Mysticeti, blue whales, which are intermittent ram suspension feeders. Have longitudinal pleats

What are the pleats of rorqual whales?

Skin flaps which allow the mouth to expand. Are on the outer lower surface of the jaw extending whole body. Pleats expand when mouth opens, and when they take in too much water they close their mouth, raise the tongue, and force water out baleen plates

Where is bubble net feeding seen?

Seen in Humpback and Bryde’s whales

How do these whales use bubble net feeding?

Whales disorient and corral small fish into a small area using a net of bubbles usually done in groups (20). A learned behavior, and they use vocalizations to make bubble nets happen

What species are in Pinnipedia (Carnivora)?

Seals, walruses, sea lions, and elephant seals

What are the two families of Pinnipedia?

Phocidae and Otaridae

What do pinnipedia look like?

They have hair and lack subdermal fat layer characteristics of whales

What is pinnipedia body type?

They have a streamlined body and are expert swimmers. Rear legs are modified as flippers which help with maneuvering or propeling

What are the reproductive habits of pinnipedia?

They spend most of their time at sea but come to beach and rocky shore to mate and rear young. Large males arrive first to establish territories while females subordinate later. Males maintain harems of one to several females and maintain territory through battles

What are the species involved with Mustelidae of sea otters (Pinnipedia)?

Otters and badgers

What are the evolved traits of the Mustelidae?

They have a streamlined body, modified appendages, and hair with an air layer that can act as a thermal barrier to slow heat loss to seawater

Are Mustelidae carnivores?

Yes they primarily prey on benthic inverts like sea urchin and mollusks, but also eat fishes

Are Mustelidae extremely important in the structure of kelp forest ecosystem?

Yes

What species are a part of Sirenians?

Manatees, dugongs, and sea cows

What is the skin type of sirenians?

They are generally hairless and streamlined where they superficially resemble whales

What is the body type of sirenians?

They have blunt, broad muzzles and their bodies are rounded with a horizontal paddle-shaped tail

How do sirenians move?

They are sluggish and live in shallow water where they eat plants and seaweeds

What are the physiological challenges of marine mammal diving?

Over long periods of time underwater, O2 is consumed but CO2 and lactic acid builds up in blood

What are the mechanisms to overcome challenges of marine mammal diving?

-increase artery volume

-storage of o2 attached to myoglobin in muscles and other globins in brain tissue preventing hypoxia

-ability to carry more oxygen per unit of blood bc of increased RBC [ ]

-decreased heartbeat and O2 consumption

-circulation more to abdominal organs

Do seals or toothed whales have an extraordinary lung capacity?

No, they are extremely efficient at absorbing o2 which is bound to hemoglobin

How do seals and whales avoid gas in their blood to bubble out of solution

-small lung capacity

-limit blood flow between lungs and circulatory system. can collapse lungs and ribs to limit gas retention

-do not breathe compressed air at depths