BIO 129 Week 1

What is a Marine Mammal?

a mammal that must get all or most of there food from the aquatic environment

What are the different taxonomic groups of marine mammals?

cetaceans, pinnipeds, sirenians, sea otters, polar bears

What are cetaceas?

whales, porpoises, dolphins

What is the first major trend in cetacean evolution and give examples?

skull morphology; telescoping, increased size, asymmetry in the skull

What is a second major trend in cetacean evolution and give examples?

tooth morphology; homodont detention, piscivorous teeth, increased number of teeth, or marked reduction of teeth to 0

What is another major trend in cetacean evolution and give examples?

changes in body form; reduction in neck function, loss of hind limbs for fluke, fusiform (elongation and streamlining), thermoregulation-blubber, increase in overall body size

What are the requirements for a mammal/cetacean to move to water?

warm shallow water, plenty of food, fewer predators, little competition

What gave rise to ancient whales/ archaeoceti?

prehistoric ungulates that came from the Tethys sea in Eocene era

What are the early archaeocetes mentioned in class?

pakicetidae, ambulocetus, remingtonocetidae, protocetidae, basilosaurus

What are the two groups of Neoceti?

Mysticeti and Odontoceti

Indohyus

the tiny “almost whale”, whale like ear structure but mostly a terrestrial body plan, ~50 mya

Pakicetidae

still legged and capable on land, feeding shifts to water, ears more specialized for hearing in water, ~48 mya

Ambulocetus

"the walking whale”, built to move through water, hind limb paddling, could still awkwardly walk on land, ~47 mya

Remingtonocetidae

“the full aquatic, still weird whales”, fully aquatic lifestyle, elongated body, long narrow snout, better underwater directional hearing, nostrils still forward, ~49-43 mya

Protocetidae

“whales break from land and spread”, pelvis starts disconnecting from the spine (hind limbs are becoming functionally irrelevant), nostrils on the move, ~49-4o mya

Basilosaurus

“final stage of archaeoceti”, approached 25 meters, no ability to move on land, nostrils shifted far back on the skull, reproduction is fully aquatic, ~41-34 mya

Neoceti

“all modern whales split into two lineages”, odontoceti (toothed whales), mysticeti (baleen whales), ~34 mya

What were some characteristics during the beginning of the Oligocene?

stronger temp gradients between poles and the equator, explosion of primary productivity, explosion of zooplankton, antarctic circumpolar current = more mixing of ocean layers, more nutrients

What are the 4 families of Mysticetes?

Balaenidae, Neobalaenidae, Eschrichtiidae, Balaenopteridae

What are the shared traits between the 4 families?

2 blow holes, symmetrical skulls, no echolocation, lower jaw articulated

What are Balaenidae and some characteristics about them?

right whales, no dorsal fin and slow moving

What are Neobalaenidae and some characteristics?

only one species the Pygmy right Whale

What Eschrichtiidae was mentioned in class and you should know about?

Gray whales, only a single species, local to monterey bay, 11-12 m, knuckles on back

What are Balaenopteridae and some characteristics?

they’re Rorqual whales, slender and streamlined (fast), dorsal fins, throat grooves, 8 species

What is the first Balaenopteridae you should know?

Blue whale, local to monterey bay, largest animal to ever live, up to 30 m long, 150 tons

What is the second Balaenopteridae you should know?

Fin whale, local to monterey bay, white cheveron on back, 21-26 m and white on lower jaw - right side only

What is third Balaenopteridae you should know?

Humpback whales, local to monterey bay, 12-15 m, long white pectoral fins, humpy backs

What is the fourth Balaenopteridae you should know?

Common Minke whale, local, white patch on front flippers, 8-10 m, dwarf and antarctic subspecies

How many families of Odontocetes and what are there shared traits?

10 families, and the share one blow hole, asymmetrical skulls, echolocation, teeth

What families fall under River dolphins?

Platanistidae, Pontoporiidae, Iniidae, Lipotidae

What are some Monodontidaes, the arctic specialists?

Narwhals and Beluga whales

What are some Kogiidaes, the sea specialists?

Pygmy sperm whale and dwarf sperm whale

What Physeteridae should you know?

Sperm whale, local, largest odontocete, massive spermaceti organ, eats primarily squid, extreme deep diving (>1000m)

What Ziphiidae should you be aware of?

Beaked whales, some local, 20+ species, weird teeth, deep divers (>3000m)

What about Delphinidae?

Dolphins, largest most diverse group, 35+ species, falcate dorsal fins, conical teeth

What is the first Delphinidae you should know about?

Bottlenose dolphin, local, spotted year round, one of the most well-studied cetaceans

What is the second Delphinidae you should know about?

Common dolphin, local, spotted year round, most abundant dolphins on earth, among the fastest, distinctive tan/yellow+gray+white coloration

What is the third Delphinidae you should know about?

Killer whale, local, dorsal fin up to 6 ft tall, divided into ‘ecotypes’

What is the fourth delphinidae you should know about?

Risso’s dolphin, local, scarring from conspecifics, no beak, squid specialists, coolest of the lot

What is the fifth Delphinidae you should know about?

Northern Right whale dolphin, local, offshore specialists, total freak

What falls under Phocoenida?

Porpoises, triangular dorsal fins, spatulate teeth, no pronounced beaks, small, scared

What Phocoenidae should you know about?

The Dall’s porpoise, which is local and the fastest, and the Harbor porpoise which is also local and is very shy

Describe the key morphological differences between Mysticeti and Odontoceti

Mysticeti have baleen plates, two blowholes, and lack echolocation, with symmetrical skulls adapted for filter feeding. Odontoceti have teeth, a single blowhole, and use echolocation, supported by asymmetrical skulls and a melon organ.

Explain how these differences relate to their feeding strategies

A Mysticeti’s features allow them to filter-feed, taking in large volumes of water and trapping small prey like krill and plankton. In contrast, Odontoceti have teeth, a single blowhole, and asymmetrical skulls with a melon organ that enables echolocation. These adaptations allow them to actively hunt and capture individual prey, such as fish and squid, by detecting and tracking them precisely, even in dark or murky environments.

Why did locomotion remain relatively conserved while feeding mechanisms diverged so dramatically?

Locomotion in whales remained relatively conserved because moving efficiently through water imposes strong physical constraints, favoring streamlined bodies, flippers, and tail flukes for propulsion and stability. In contrast, feeding mechanisms diverged dramatically as whales adapted to exploit different ecological niches: Mysticeti evolved baleen and filter-feeding to consume abundant small prey, while Odontoceti evolved teeth and echolocation to hunt individual prey.