Exam 1 - Lecture 3: Cetaceans

what 3 traits did early whales have?

teeth, non-existent rear appendages, modified flipper and tail

Order Cetacea

• what organisms does it contain and how many in total

• what general location does it live

• describe its body shape

• describe ear

• what is unique about its bones?

• describe hair

• define blowhole

• how does it thermoregulate

• describe tail, what does it end in

• whales, dolphins, porpoises (~90 spp) all marine except for 5 FW dolphins

• completely aquatic bc highly modified to do so

• body is fusiform/torpedo shapes => ocean has caused convergent evolution bc this is also seen in seals and sea lions

• ear is internal bc the skin has sealed it off to limit any water that can enter decreasing infection risks, there is no external hole or pinnae

• has oil-filled bones to increase buoyancy (also reason it was hunted)

• little to no hair (so this is a mammal characterisitic that has been lost over time to increase streamline)

• blowholes are used to release ONLY air

• dorsal fin is used for thermoregulation by shunting the blood to the fin so that heat can be lost

• muscular tail ends in fin-like horizontal flukes that stay flat and moves up and down to swim

what are the 2 suborders?

Mysticeti and Odontoceti

Order Cetacea

Suborder Mysticeti

• what general types of animals does it contain?

• describe mouth

• describe blow hole

• describe sexual dimorphism

• baleen whales

• baleen plates filter organisms from the water w/ brush-like plate of keratin

• double blow hole = 2 openings/nares under muscular control that closes in the water (looks like horse nostrils migrated on top of head)

• reverse sexual dimorphism: female > male

Order Cetacea

Suborder Odontoceti

• what general types of animals does it contain?

• describe mouth

• describe blow hole

• describe sexual dimorphism

• toothed whales

• teeth on one or both jaws

• single blow whole

• males > females

describe the baleen feeding of Blue Whales and Right whales

• Blue whales have accordion folds that can expand to gulp LOTS of water

• Right whales have bigger baleen but no accordion folds so just holds the amount of water it can with its mouth

• Both animals move tongue to top of mouth => water is strained/pushed out on sides of mouth

Order Cetacea

Suborder Mysticeti

what are the 3 families

Balaenidae, Neobalenidae, and Balaenopteridae

Order Cetacea

Suborder Mysticeti

Family Balaenidae

• what general organism does this consist of

• what structure is it lacking

• what is general body shape

• Right whales and bowhead whales

• lacking accordion folds/mouth grooves

• body

  • huge bulky whales

  • no dorsal fin or ridge

  • distinclty arched mouths w/ baleen plates up to 5m

why are they called Right whales?

“right whales to hunt bc…

1. swims close to shore (no large steam vessels needed)

2. slow swimmer = Leviathans

3. produce lots of oil

4. float when dead so easier to collect and tow to shore

Order Cetacea

Suborder Mysticeti

Family Balaenidae

Eubalaena glacialis

• aka

• IUCN

• North Atlantic right whale (“eu” = true)

• endangered (still bc constantly hit by ships)

Order Cetacea

Suborder Mysticeti

Family Balaenidae

Eubalaena japonica

• aka

• IUCN

• North Pacific right whale

• Endangered

Order Cetacea

Suborder Mysticeti

Family Balaenidae

Eubalaena australis

• aka

• IUCN

• South Pacific right whale

• lower risk, conservation department

Order Cetacea

Suborder Mysticeti

Family Balaenidae

Balaena mysticetus

• aka

• what what whale does it resemble, how does it differ (i.e., what’s lacking and what is present)

• IUCN

• Bowhead

• resembles Right Whales but is missing callosities (callus-like facial structures seen in right whales, can have lice) and has a distinct neck region signified by notch behind head

• critically endangered

Order Cetacea

Suborder Mysticeti

Family Neobalaenidae

• what general organism does this consist of

• what was it confused w/ and why

• what structures does it contain

• describe body and mouth

• IUCN

• pygmy right whale

• was thought to be a right whale, but this is not the case it just overlaps in geographic location as Southern right whale

• 2 throat grooves, dorsal fin

• slender body, arched jaw line, SMALLEST baleen whale

• IUCN = unknown bc they do not breech the water often

Order Cetacea

Suborder Mysticeti

Family Balaenopteridae

• what organism does it contain

• how do they feed

• describe body shape

• describe baleen

• where does it live

• Rorquals

• feed by gulping up schools of fish and krill with throat grooves

• long and slender whales

• baleen is short w/ no jaw line arch

• cosmopolitan distribution = makes great migration in ocean, no distinct region

Order Cetacea

Suborder Mysticeti

Family Balaenopteridae

Balaenoptera musculus

• aka

• describe body shape and color

• how many subspecies

• where does it live

• IUCN

• Blue whale (“musculus” = little mouth)

• slender and streamlined body, bluish gray in color

• 3 subspecies: North Atlantic, North Pacific, and Southern Ocean (some interbreeding occurs w/ subspecies)

• lives across globe in every ocean basin

• endangered

Order Cetacea

Suborder Mysticeti

Family Balaenopteridae

Balaenoptera physalus

• aka

• describe body shape and color

• where does it live

• IUCN

• fin whale

• pointed head, sleek and streamlined; countershading

• equally as cosmopolitan as blue whale

• endangered

Order Cetacea

Suborder Mysticeti

Family Balaenopteridae

Balaenoptera borealis

• aka

• describe body shape and size

• where does it live

• IUCN

• Sei whale

• sleek and streamlined, 3rd largest whale at 14-18m

• avoids polar and tropical waters, but still has large cosmopolitan distribution and some areas may be data deficient

• endangered

Order Cetacea

Suborder Mysticeti

Family Balaenopteridae

Balaenoptera brydei

• aka

• describe unique morphological feature

• Bryde’s whale

• contains 3 prominent ridges on rostrum

Order Cetacea

Suborder Mysticeti

Family Balaenopteridae

Balaenoptera omurai

• aka

• where does it live

• Omura’s whale

• distributed more in Pacific waters

Order Cetacea

Suborder Mysticeti

Family Balaenopteridae

Balaenoptera ricei

• aka

• where does it live

• Rice’s whale

• Gulf of Mexico resident

• described in 2021 as a unique population of Bryde’s whale bc had 3 ridged on head BUT is a genetically distinct sp.

Order Cetacea

Suborder Mysticeti

Family Balaenopteridae

Balaenoptera acutorostrata

• aka

• describe body shape and color

• how many subspecies

• where does it live

• IUCN

• Common minke whale

• distinctive coloration

• 3 subspecies: Standard minke whale, dwarf minke whale, and used to include Antarctic minke whale (but now is separate sp.)

• some sp. live in northern parts of ocean while others live in southern parts and can overlap each other

• near threatened

Order Cetacea

Suborder Mysticeti

Family Balaenopteridae

Balaenoptera bonaerensis

• aka

• Antarctic minke whale

• this is a renamed sp.

Order Cetacea

Suborder Mysticeti

Family Balaenopteridae

Megaptera novaeangliae

• aka

• describe body shape (body, flippers, tail)

• notable behavior

• describe feeding mechanism and location

• where does it give birth

• IUCN

• Humpback whale

• robust body, long flippers w/ tubercles, tail fluke w/ serrated edge

• known for breaching and slapping water (thought to dislodge parasites and communicate)

• LOTS of accordion folds, feeds in summer in polar waters

• migrates from poles to tropical/subtropical waters to give birth; will have 1 calf

• vulnerable

Order Cetacea

Suborder Mysticeti

Family Eschrichtiidae

Eschrichtius robustus

• aka

• what is significant about its evolutionary history

• # of throat grooves

• presence/absence dorsal fin

• define crenellations

• where can it be found, and how does it affect the sp?

• what is a natural predator of this sp?

• IUCN

• Gray whale

• most primitive of baleen whales

• 2-5 throat grooves

• no dorsal fin

• crenellations = series of low humps on back that aid in stability and swimming; also thought to be a precursor to dorsal fins

• stays near the coast (so does not live in pelagic zone) making it vulnerable

• orca whale is a natural predator of calves

• critically endangered

Order Cetacea

Suborder Odontoceti

• aka

• size and shape of the whales

• define echolocation

• hunting ability

• define melon

• toothed whales

• small-medium sized whales, streamlined bodies

• echolocation = ability to use sonar

• can stun prey w/ sonic bursts; does not eat schools of organisms only 1 individual at a time

• melon = fatty organ in forehead area made of lipids used for echolocation

describe the process of echolocation

1) emits sound from larynx (the voice box in the throat) through ring of muscle => 2) focused and directed by the melon as the sound goes through the melon => 3) sound hits an object and is reflected back => 4) heard through the acoustic window (which is a transparent, oil-filled bone) => 5) goes to the inner ear => 6) signal moved to brain to determine information, so that the time it takes the echo to return indicated how far away the object is, size of prey, and direction or prey

Order Cetacea

Suborder Odontoceti

Family Physeteridae

Physeter macrocephalus

• aka, what does sp. name mean

• describe size, flippers

• what is a unique morphological trait

• describe its teeth

• how deep does it dive

• describe the size difference between males and females

• describe distribution

• how does it sleep

• Sperm whale (Physeter macrocephalus)

• largest toothed whale, short and wide flippers