Module 8 Flashcards
Cetaceans
Describe how the branches of artiodactyla are organized.
The first lineage to diverge is Tylopoda (camels, llamas, guanacos, alpacas and vicuñas).
Next to diverge is Suina (a suborder of omnivorous, non-ruminant artiodactyl mammals that includes the domestic pig and peccaries).
Then Ruminant (cattle, sheep, goat, deer, giraffe)
We then have Whippomorpha, which is comprised of Hippopotamidae and Cetacea.
What is Andrewsarchus?
A carnivorous, “hooved” animal with long and powerful jaws with crushing teeth. Ate their relatives, hooved ungulates.
A whippomorph, extinct relative to the hippopotamus and cetaceans.
Describe the evolution of traits that took place over millions of years that started at the hippopotamus and resulted in Mysticetes (baleen whales).
(1) Hippo 55 million years ago
(2) Thick, bony wall around the middle ear; freshwater semi-aquatic habitat (~45-50 mya)
(3) Large powerful tail, shorter legs, fat pad in jaw for hearing underwater, brackish water habitat. (around the same time-ish)
(4) Moves to saltwater habitat (~45 mya)
(5) Nasal opening shifted back, eyes on the side of head
(6) Tail flukes, very small hind legs, nasal opening shifted further back (40-45 mya)
(7) Marks the divergence of modern Cetaceans; complete loss of hind legs, nasal openings reaches position of blowhole in living whales (~40 mya)
(8) Odontocetes develops echolocation for hunting and Mysticetes develops baleen for filtering food
What is the evolutionary significance of extinct Pakicetus inachus?
~50 mya
Distant cousin to the hippopotamus and early on in the evolutionary lineage of Cetaceans.
Possesses a thick, bony wall around the middle ear (separating them from hippos) and was freshwater semi-aquatic.
Who’s this diva?
Ambulocetus
Ancestor to cetaceans and cousin to the hippo (extinct).
Possesses thick, bony wall around middle ear, freshwater semi-aquatic lifestyle, large powerful tail, shorter legs, fat pad in jaw for underwater hearing, and brackish water habitat
Who is this diva?
Remingtonocetus from the middle Eocene (47.8–40.4 Mya)
Ancient cetacean
Convergent evolution with the platypus
Who is this diva?
Rodhocetus
“Rodhocetus was a small whale measuring 2–3 m (6.6–9.8 ft) long”
Possess thick, bony wall around middle ear, large powerful tail, shorter legs, fat pad in jaw for underwater hearing, and saltwater habitat, nasal openings are shifted back, eyes on sides of head.
Decendent that came before the evolution of tail flukes in cetaceans and the gradual loss of hind limbs.
True or false? The ankle bone of Rodhocetus are more similar to artiodactyls (even-toed ungulates) than the traditional mesonychian ancestor.
“Throughout the 1990s, a close relationship between cetaceans and mesonychians, an extinct group of cursorial, wolf-like ungulates, was generally accepted based on morphological analyses. In the late 1990s, however, cladistic analyses based on molecular data clearly placed Cetacea within the Artiodactyla near the hippopotamus. One of the diagnostic characteristics of artiodactyls is the double-pulley astragalus (ankle bone), and palaeontologists, unconvinced by the data from the labs, set themselves out to find archaeocete single-pulley heel bones. Hind legs from three archaeocete species were recovered within a few years, among them those of Rodhocetus balochistanensis, and all three had double-pulley heel bones, thus settling the cladistic controversy.” -Wikipedia
Describe “King Lizard’s” lore.
Basilosaurus is a genus of large, predatory, prehistoric archaeocete whale from the late Eocene, approximately 41.3 to 33.9 million years ago.
First described in 1834, it was the first archaeocete and prehistoric whale known to science.
- Originally thought to be of a giant reptile
- Later found to be an early marine mammal
Dorudon is a genus of extinct basilosaurid ancient whales that lived alongside Basilosaurus 41.03 to 33.9 million years ago in the Eocene.
How many limbs did they have? Why is this information important?
Four
Note the retention of the hind limbs, feet, and toes like those found in Basilosaurus.
It is important because it helps explain the retention of vistigial hip bones in modern whales.
Describe the evolution of nasal openings in whales.
The ancient, amphibious whale Pakicetus had a land mammal’s nostrils at the end of the snout.
Rodhocetrus swam the seas; its nostrils were higher on the skull, intermediate to those of its ancestors and modern whales.
A modern grey whale’s blowhole allows it to break the surface, inhale, and re-submerge without having to stop or tilt the snout up.
Describe the evolution of hearing in whales.
Though more aquatic than Pakicetus, Ambulacetus still heard directly through their ears.
Sounds were transmitted to the middle ears of Basilosaurus as vibrations from the lower jaw.
Modern toothed-whales echolocate; the melon directs sounds at an object, and the lower jaw receives the echoing reply.
True or false? Sperm whales are most closely related to baleen whales of the toothed-whales.
True
Describe the evolution of baleen filter feeding in whales.
Name six types of baleen whales (common names).
(1) Blue whale
(2) Humpback whale
(3) Fin whale
(4) Bowhead whale
(5) Grey whale
(6) Minke whale
Name eight types of toothed whales (common names).
(1.1) Sperm whale
(1.2) Award sperm whale
(1.3) Pygmy sperm whale
(2) Cuvier’s beaked whale
(4) Bottlenose dolphin
(5) Orca/killer whales
(6) Beluga whale
(7) Porpouse
(8) River dolphins
Describe the biological process if of echolocation in toothed whales.
(1) The air is pushed through the nasal cavities creating a vibration with the phonic lips that produce the sound waves
(2) The sound waves reflect off an object and are sent to the inner ear by fat bodies in the jaw and melon
(3) The cochlea contains specialized hair cells that react to different frequencies of sound. Each hair can sense a particular sound wave, amplify the signal, and transmit it later to the brain
- The brain interprets distance the waves reflect off of and maybe even the shape depending on the acoustics
How do whales equal out the bouncy of their blubber?
By having dense bones
How are whales adapted to maintain their body temperature?
Whales use a cross-current heat-exchange system.
How are sperm whales adapted to hunting squid deep in the ocean?
Anatomical and physiological adaptations enable sperm whales to make these long deep dives. These include a flexible ribcage that enables their lungs to collapse safely under increased water pressure; a large blood volume very high in oxygen- carrying hemoglobin; an increased amount of myoglobin, a protein that stores high levels of oxygen in muscle tissue; and the ability to direct oxygenated blood to areas of critical need such as the brain when oxygen supplies are depleted which is also when metabolism rates decrease. In addition the blubber of sperm whales is 15 to 30 cm (5.9 to 11.8 in) thick. It insulates the whales so they can dive to great depths in water that is just above freezing and allows them to maintain a high core body temperature without losing heat to their surroundings.
https://www.aquariumofpacific.org/onlinelearningcenter/species/sperm_whale#:~:text=These%20include%20a%20flexible%20ribcage,direct%20oxygenated%20blood%20to%20areas
What is the most extreme diving mammal?
Cuvier’s Beaked whale
How do marine mammals avoid getting the bends when deep sea diving?
Marine mammals fill their blood with oxygen then exhale before diving deeply. This is called oxygen loading.
They also conserve blood flow to essential tissues and have flexible ribcages to withstand the increased pressure.
How are high altitude terrestrial mammals like llamas similar to deep diving marine mammals?
Both have evolved to have greater binding sites in red blood cells to oxygen load their blood. This helps them survive the low oxygen content in their respective habitats.
Why are adaptations in pinnipeds so similar to that in whales?
They are following the same evolutionary trajectory as whales/dolphins but are a few million years behind.
Name fourteen types of pinnipeds (common names).
(1) Harbor seal
(2) Ribbon seal
(3) Gray seal
(4) Southern elephant seal
(5) Hawaiian monk seal
(6) Spotted seal
(7) Steller sea lion
(8) Northern fur seal
(9) Leopard seal
(10) Ringed seal
(11) Harp seal
(12) California sea lion
(13) Hooded seal
(14) Pacific walrus
Where are pinnipeds situated in Carnivora cladistically?
Who is Puijila darwini and why should we care?
Puijila darwini is an extinct species of stem-pinniped which lived during the Miocene about 21 to 24 million years ago. About a metre long, the animal had only minimal physical adaptations for swimming.
What carnivore are stem pinnipeds most closely related to?
Bears (ursidae)
Who is Enaliarctos?
Enaliarctos is an extinct genus of pinnipedimorph from 24-22 mya (Oligocene-Miocene), and may represent the ancestor to all pinnipeds.
What are the six classifications of seals?
(1) earless seals (true seals)
(2) eared seal (sea lions and fur seals)
Eared seals (sea lions and fur seals) have visible external ear flaps and can rotate their hind flippers to walk on land, while earless seals (true seals) lack these flaps and move on land by “galumphing” (moving on their bellies).
The order Sirenia is comprised of what two families?
Dugongidae (1 spp.)
Trichechidae (3 spp.– but one species gas two subspecies)
What is the quickest and easiest identified characteristic that differentiates the manatee and the dugong?
The manatee has a non-forked tail
The dugong has a forked tail
What likely caused the extinction of the Stellar sea cow (Northern dugong)?
Whaling/overhunting
Steller’s “sea cow”, a very large sirenian of the North Pacific, hunted to extinction 27 years after it’s discovery (mid 1700s)
Sirenians share a common ancestor with ______.
Sirenians share a common ancestor with elephants!
Elephants have many traits suited for marine or aquatic life, such as water conserving kidneys and internal testes.
What are the main characteristics of Sirenia?
Like whales, sirenians never leave the water.
Strictly herbivores
Inhabit coastal areas, estuaries, and bays
Need warm water (low metabolic rates)
Name adaptations that are examples of convergent evolution with whales.
(1) Hairless, fusiform shapes, no external ears, no hind-limbs, tail flattened, blubber
(2) Skeletal bones very dense (to help overcome buoyancy)
(3) Lungs are long, thin, dorsal in abdominal cavity
(4) Like elephants, cheek teeth are replaced horizontally
What are the two main challenges regarding the conservation of Sirenians?
(1) Very slow to reproduce (one calf every 3-5 years)
(2) All living species endangered
