Order Cetacea Mammalogy

What is the order and suborder of baleen whales?

Order Cetacea

Suborder Mysticeti

What is the order and suborder of toothed whales (dolphins, orcas)?

Order Cetacea

Suborder Odontoceti

Where were archaic whales, archaeocetes, first seen?

Tethys Sea

Fossil and molecular studies suggest whales are closely related to which group?

artiodactyls, w hippopotamus as closest relative

Which structure indicates a common ancestor between Cetaceans and Artiodactyls?

synapomorphic astragalus (ankle bone)

Synapomorphic character

trait shared by 2 or more taxa and inferred to have been present in most recent common ancestor

Describe the body plan of modern cetaceans:

• fusiform body

• forelimbs = flippers (no nails or claws)

• hindlimbs vestigial

Describe the tail of cetaceans

has horizontal flukes for power

Describe insulation of cetaceans

nearly hairless w thick layer of blubber

What are the hindlimbs of cetaceans reduced to?

vestigial innominate bones

Which bones in cetaceans are for muscles attachment?

chevron bones

Which vertebrae of cetaceans are usually fused?

cervical vertebrae

Describe how the forelimbs of cetaceans are modified as flippers:

• shortened humerus, radius, ulna

• elongated digits by increasing # of phalanges (hyperphalangy)

What’s the primary difference between the 2 suborders of cetaceans (mysticeti, odontoceti)?

• Mysticeti have baleen

• Odontoceti have homodont, peg-like, simple teeth

Which cetaceans are monophyodont, Odontocetes or Mysticeti?

Odontocetes

How does a fin whale’s oral/buccal cavity grow as the whale grows?

it does not scale linearly, instead the cavity takes up a larger percentage of its body size

• engulfment capacity rises from 75% to 133% of body mass

What allows the whale’s lunge to occur in 10 secs?

• sensory structures w nerve endings at front tip of lower jaws

• send signals to brain

• trigger whales’ feeding lunge

What are the 3 cahmbers in the cetacean stomach?

1. 1st chamber has muscular walls

2. 2nd has digestive enzymes/acid (main chamber)

3. 3rd is pyloric stomach

What is “telescoping” in cetaceans?

process of skull becoming highly modified as result of posterior migration of external nares

Which bones form most of the roof of the cetacean skull anteriorly?

pre-maxillary and maxillary bones, w some of frontal

Blow holes of toothed vs baleen whales:

• toothed = single blowhole

  • baleen = 2 blowholes

In which suborder of cetaceans are the nostrils NOT fused, instead on has become dominant over the other?

Odontocetes

How have odontocete skulls changed as they adapted for echolocation?

skulls became asymmetric

Which suborder of order cetacea has poor connection between the 2 hemispheres of the brain?

suborder odontocete

Which organ in odontocetes is used as a lens to focus sound waves?

melon

How are sounds of odontocetes produced?

no vocal cords, produced thru blowhole system

Which senses/structures have whales lost?

smell and salivary glands

Describe the auditory bulla in most cetaceans:

not attached to skull, partly insulated from rest of cranium by surrounding air sinuses and soft tissue

Which family of suborder Mysticeti has a series of throat grooves that allow mouth to expand when feeding?

Family Balaenopteridae (blue whale, fin whale, humpback, etc)

What are the longitudinal folds of skin running from below mouth back to navel of Balaenopteridae whales?

throat grooves

Rorquals

Balaenopteridae whales

Which family of suborder Mysticeti is slender, streamlined, have mostly narrow elongated flippers, and dorsal fin?

Family Balaenopteridae (rorquals)

Most rorquals are strictly _____

oceanic

What is the family and suborder of the Gray whale?

• Family Eschrichtiidae

  • Suborder Mysticeti

Which family of suborder Mysteiceti exhibits bottom feeding?

family Eschrictiidae (gray whales)

What is the family and suborder of the Right and Bowhead whales?

• Family Balaenidae

  • Suborder Mysticeti

Which family of Mysticetes has a narrow, arched, upper jaw, giving a deeply curved jawline?

Family Balaenidae

Which family of Mysticetes feeds by surface skimming?

Balaenidae

Which family of Mysticetes lacks throat grooves and has exceptionally large heads which reach 40% of total length of body?

Balaenids

What is the family and suborder of the pygmy right whale?

Family Neobalaenidae, Suborder Mysticeti

Which is the smallest of the baleen whales?

Neobalaenidae, pygmy right whale

What is the family and suborder of oceanic dolphins?

Family Delphinidae, Suborder Odontoceti

What are the feeding habits of delphinids?

all carnivorous

Family and suborder of porpoises:

Family Phocoenidae, suborder Odontoceti

Porpoises compared to dolphins:

• smaller and stouter than dolphins

• blunt jaws instead of beaks

• no bulbous melon

• triangular dorsal fun, not curved

Describe skull of porpoises (Phocoenids)

small rounded heads and blunt jaws

Family and suborder of Narwhals and belugas:

Family Monodontidae, Suborder Odontoceti

Which family of suborder Odontoceti does NOT have a true dorsal fin, but instead has a narrow ridge running along the back?

Family Monodontidae

Which family of Odontocetes has a melon and short or absent snout?

Monodontids

Are porpoises social?

form smaller groups

Are belugas social?

highly sociable, male groups can number in hundreds

Teeth of narwhal (monodontidae)

only 2 teeth, one of which forms tusk in males

Describe the tusk of a narwhal (monodontidae)

enlarged incisor

• sense changes in environment

  • no enamel

Describe layers of narwhal tusk

• outer cementum layer is porous

• inner dentin layer = microscopic tubes

• middle = pulp = nerve endings sensitive to temperature and salinity

In which family of suborder Odontoceti is the cervical vertebrae not fused, unlike many cetaceans?

Monodontidae and Iniidae

Family and suborder of Boto, Baiji, and Franciscana

Family Iniidae, Suborder Odontoceti

Family and suborder of Ganges and Indus river dolphins

Family Platanistidae, Suborder Odontoceti

Which family of odontocetes has teeth that are always visible in both upper and lower jaws, even when mouth is closed?

Family Platanistidae

Which family of Odontocetes does not have a crystalline eye lens = effectively blind = rely on echolocation for navigation and hunting?

Family platanistidae

Family and Suborder of beaked whales

Family Ziphiidae, suborder Odontoceti

Which family of Odontocetes has a pair of converging grooves under throat, small dorsal fin, and absence of notch in tail fluke?

Family Ziphiidae

Feeding habits of Ziphiiidae, beaked whales

deep ocean feeders

Which family of odontocetes has only one or two pairs of teeth, which do not erupt in females

Ziphiidae

Which family of odontocetes has sexual dimorphism w the females being larger and males have bulging forehead?

beaked whales, Family Ziphiidae

Which are the only marine mammals that their evolution is believed to have been shaped by secondary sexual characteristic?

Family Ziphiidae, beaked whales

What is the feeding mechanism of beaked whales, Family Ziphiidae?

suction feeding

Which family of Odontocetes uses suction feeding?

Family Ziphiidae, beaked whales

What is the family and suborder of sperm whales?

Family Physeteridae, Suborder Odontoceti

What is the largest species/family of Odontocetes?

Sperm whale = Family Physteridae

What is distinct about sperm whales, Physteridae?

asymmetrical nasal bones w blowhole on left side of head

In which family of Odontocetes is the lower jaw always small and thin relative to upper jaw, and the teeth in upper jaw do not erupt or smtimes absent altogether?

Family Physteridae, sperm whale

Why is it likely that echolocation is more important in sperm whales than vision?

bc they can’t swivel eyes in socket and only possess vestigial anterior chamber

Which family of Odontocetes has a spermaceti = waxy substance filling organ in whale’s head which acts as ballast?

• Family Physteridae, sperm whale

• Family Kogiidae

Spermaceti

semi-liquid waxy substance filling spermaceti organ in sperm whale’s head, which acts as ballast in diving and maintaining buoyancy

How do whales use spermaceti to dive and maintain buoyancy?

• cold water thru nose to harden spermaceti and dive

• pump warm blood to melt spermaceti, rise

Family and suborder of pygmy/dwarf sperm whales

Family Kogiidae, Suborder Odontoceti

Which family of Odontocetes will expel a dark red fluid when frightened?

Family Kogiidae, dwarf sperm whales

Which family of Odontocetes has large head compared to body, small and low lower jaw, and false gill slit behind each eye?

Kogiidae

rat porpoise

Kogiidae bc have btwn 20 to 32 teeth, all in lower jaw