MIDTERM STUDY GUIDE

Early archaeocetes such as Pakicetus were closely related to mammals in the Order Carnivora, such as the modern wolf. True False

false

The only herbivorous marine mammals are in the Order [1].

Sirenia

The _____ of the sperm whale is homologous with the melon of other odontocetes.

junk

Whalebone is composed of

keratin

Extant (living) marine mammals are classified in ___ orders.

3

Identify the correct taxonomic family of each labeled image. A. orca B. manatee C. otter D. Walrus E. polar bear F. baleen whale

A Delphinidae B Trichechidae C Mustelidae D Odobenidae E Ursidae F Balaenopteridae

Match the following families with their most common feeding strategy. surface skimming lunge feeding bottom suction feeding "wave" hunting

Balaenidae Balaenopteridae Eschrichtiidae Delphinidae

Cetaceans and sirenians are both characterized as a having fully aquatic lifestyle, while pinnipeds and polar bears spend some part of their life on land. What is a likely factor in these divergent life history patterns?

Cetaceans and sirenians evolved before pinnipeds and polar bears in evolutionary time (early Eocene). Therefore, they have had more time to evolve towards a fully aquatic lifestyle, whereas pinnipeds only evolved 20 mya and polar bears are also evolutionarily newer. This is likely a large factor in their divergent life history patterns. Some pinnipeds still have earflaps and can turn their hind limbs forward in order to walk on land. There are some families of pinnipeds like phocidae that don't have earflaps and cannot walk on land, so they are more evolved for an aquatic lifestyle, but still not as much compared to whales or manatees which have had more time to evolve and adapt to a fully aquatic lifestyle. Polar bears can swim for limited periods of time and rely on the ocean for food and sea ice for habitat, but that is the extent of their adaptations for the ocean/water. Cetaceans and sirenians are much better adapted to marine life. For example, they have no hind limbs or flippers at all. They have had more millions of years to adapt and evolve to be fully aquatic.

From a biogeographical perspective, the assignment of Desmostylia† to the Superorder Afrotheria has always been problematic. Why?

Desmothylia was not found in Africa, which all other Afrotherians are. The skull structure of desmothylians has been found to be similar to elephants, manatees and dugongs, however they have only been found in North Pacific Basin, not in Africa which is problematic because Afrotherians are supposed to be from Africa.

Based on the paper, which of these strategies have marine mammals evolved to cope with the lack of oxygen during diving? (Check all apply) Enhanced tissue oxygen stores Low basal metabolic rate (compared to terrestrial mammals) Increased buffering capacities conferring greater tolerance to hypoxia Altered oxygen transport to select organs Reduced number of dives during the reproductive season

Enhanced tissue oxygen stores Increased buffering capacities conferring greater tolerance to hypoxia Altered oxygen transport to select organs

True or False: The diving reflex is unique to marine mammals.

False

The authors give two different hypotheses to explain the independent evolution of giant body size in Mysticetes and Odontocetes. What are these two hypotheses?

For Mysticetes, the authors hypothesized that they evolved to have large body sizes in order to more efficiently capture patches of their smaller, low trophic level prey (such as krill). The authors also hypothesized that odontocetes evolved larger body sizes to increase their diving capacity and enhance their biosmar skills for capturing larger deep-sea prey.

The extant (still-living) sister group to Cetacea is: Sirenia (manatees and dugongs) Basilosauridae (basilosaurus) Bovidae (cows) Hippopotamidae (hippopotamuses)

Hippopotamidae (hippopotamuses)

Phonic lips would be found in which of these families? Monodontidae Delphinidae Ziphiidae Physeteridae Trichechidae Balaenopteridae

Monodontidae Delphinidae Ziphiidae Physeteridae

Identify the cetacean crown groups. Odontoceti Mysticeti Archaeoceti

Odontoceti Mysticeti

Identify the habitat in which these taxa would have been found. Pakicetidae Remingtonicetidae Basilosauridae

Pakicetidae fresh-water adjacent Remingtonicetidae nearshore marine Basilosauridae pelagic

River dolphins share several features in common as a result of having adapted to similar niches. Identify (name) one of the convergent morphologies we observe in river dolphins and give an explanation of its adaptive significance.

River dolphins species have unfused cervical vertebrae. They don't really have necks, so this prevents the neck from moving back and forth; the vertebrae can swivel around, so the neck vertebrae are often fused together in dolphins. However river dolphins have an unfused neck allowing them to forage more selectively through the dense vegetation of river basins. They also have wide paddle-like pectoral fins to help navigate through vegetation. All of the river dolphins species seem to live in river basins of highly vegetated rain forests or highly vegetated areas. River dolphins also have a tendency for their dorsal fins to be really reduced or absent. The dorsal fins can get tangled in vegetation from the flooded terrestrial planes that these dolphins live in.

Weddell seals and people of the Bajau tribe share this adaptation: they both have an enlarged organ that stores oxygenated red blood cells. Which organ is it? Liver Galbladder Heart Spleen

Spleen

The paper identifies blue, fin, and humpback whales as especially vulnerable to noise from ocean shipping traffic. Why are these whales so heavily impacted by anthropogenic noise?

The frequency of noise produced by ships traveling through the marine protected area is similar low frequencies to these whale species calls. Therefore, the low frequency noise can mask their calls to one another and obstruct communication between individuals of these species. It disturbs the habitat, communication between individuals and makes them more susceptible to predation, getting lost from their group, and other issues.

How do we know that early mysticetes had teeth and baleen at the same time?

The nutrient foramina, grooves, and sulci present in the skull.

While researching walruses on the internet, you come across this statement in a species account: "The Walrus exhibits sexual dimorphism in that males evolved to have long, big tusks while females do not have tusks. The male tusks develop from upper incisors." Is this statement correct? If not, how would you change it?

This is not correct. Tusks and canines, not incisors. Also, both male and female walruses have tusks. A better way to see their sexual dimorphism is to look at body size. Male walruses are much larger than females and they also practice polygyny, where one male mates with multiple females.

Compared to other marine mammals, which family has the lowest basal metabolic rate relative to body size? Trichechidae Delphinidae Mustelidae Phocidae

Trichechidae (manatees and dugongs)

Give a reason why industrial whaling drastically declined during the 1945 indicated by the red arrow on this graph:

WWII

Discuss two different adaptations we observe in deep diving marine mammals. Explain how those adaptations are useful to an aquatic mammal.

Whales have flexible ribs. This allows their rib cages to collapse when they dive into deep waters and are exposed to extreme pressures. Whales also have thick tissue around the ears. This tissue protects the inner ear bones from rupture or damage under the extreme pressures of the deep ocean that may be experienced in deep dives.

The earwax plug found in large baleen whales has been used to: (check all that apply) determine exposure to pollutants determine age at death determine age that sexual maturity was reached determine periods of stress

all apply

Which of the following is true of blubber? a. Provides buoyancy b. Is part of the integumentary system c. Is present in all marine mammals d. Helps to smooth the skin surface e. Is an important heat insulator

all are true except: c. Is present in all marine mammals

The blood volume relative to body mass is impressively high in the deepest diving marine mammals. Identify one adaptation for an increased blood volume:

any of the following: retia mirabile enlarged spleen big spleen large spleen

What is the taxonomic Order in which living whales and dolphins are categorized?

artiodactyla

What is the best explanation for female polar bears exhibiting induced ovulation? female choice (can pick the father of her cubs) cubs will be born at optimal time of year to ensure the birth of twins avoids wasting of gametes

avoids wasting of gametes

Cetaceans and sirenians swim using pelvic oscillations [__________] movement of the tail flukes produces forward thrust. The alternating actions of the [__________] muscles drive the movement of the flukes.

caudal epaxial and hypaxial

The species richness of toothed whales is highest in: continental coastlines southern polar seas northern polar seas deep ocean basins

continental coastlines

The cetacean species with the deepest and longest recorded dive is the [ Select ] ["sperm whale", "Cuvier's beaked whale", "killer whale", "blue whale"] . The pinniped species with the deepest and longest recorded dive is the [ Select ] ["walrus", "elephant seal", "California sea lion", "Weddell seal"] .

cuviers beaked whale elephant seal

The closest living relatives of the sea cows (Order Sirenia) are the _________.

elephants

Match the appropriate geologic time period with the following important events in marine mammal evolution. first appearance of cetaceans- First appearance of sirenians - First appearance of polar bears - Fur seals disperse to the southern oceans -

first appearance of cetaceans- Early Eocene First appearance of sirenians - early Eocene First appearance of polar bears - Pleistocene Fur seals disperse to the southern oceans - Pleistocene

The long, narrow flippers in humpback whales are an example of ______ aspect ratio hydrofoils. These wing-like flippers are an adaptation for ______ maneuverability .

high aspect ratio high maneuverability

Marine mammals have [_____] basal metabolic rates compared to terrestrial mammals of the same mass. At the water's surface, marine mammals have [______] resting heart rates compared to terrestrial mammals of the same mass; during dives, marine mammals have much [______] resting

higher higher lower

The primary diet of the crabeater seal (Phocidae)

krill

Mysticetes produce ______ frequency sounds that attenuate ________. Odontocetes produce ______ sounds that attenuate ______.

low slow high quickly

The phenomenon of one acoustic signal covering up another one (for example, noise from ships covering up whale vocalizations) is called: Masking Attenuation Harmonization Transmission

masking

According to the diphyletic hypothesis of pinniped origins, the Phocidae are derived from a(n) [_________] ancestor, the Otariidae are derived from a(n) ________ ancestor, and the Odobenidae are derived from a(n) [_________] ancestor. According to the monophyletic hypothesis of pinniped origins, the Phocidae are derived from a(n) [_________] ancestor, the Otariidae are derived from a(n) [_________] ancestor, and the Odobenidae are derived from a(n) [_________] ancestor. (monophyletic says they are all from mustelids)

mustelid-like ursid-like ursid mustelid mustelid mustelid

Male dugongids have tusk-like incisors, which is evidence they have a _________ mating system. polygynous promiscous

polygynous

Basal pinnipedimorphs in the genus Enaliarctos† have been extinct for more than 20 million years, but we can still learn things about their life history. For example, size differences between male and female Enaliarctos† skulls suggest they were likely:

polygynous (1 male mated with many females)

According to the phylogeny provided here, the "river dolphins" would comprise a ______ group

polyphyletic

The three-dimensional environment of the ocean has led to most cetacean species exhibiting this general mating strategy: polygyny monogamy polyandry promiscuity celibacy

promiscuity

Which cladogram represents our current understanding of the evolutionary relationships of pinnipeds?

the third one in the image

The first mysticetes lacked baleen and had teeth. True False

true

Pick one phenotypic trait (section 3.3, pg. 14) that cetaceans have that you find most interesting and briefly describe how that trait is adaptive to a fully marine lifestyle.

A phenotypic trait I found interesting was that cetaceans have adapted to be "nearly hairless" and that their skin has no sweat glands or sebaceous glands. These adaptations allow cetaceans them to be extremely smooth externally and travel through the water more hydrodynamically/reduce drag while swimming. Evolutionarily, if their drag is reduced this allows cetaceans to use less energy while swimming, hunting, etc. and be more efficient animals overall.

Match the locomotion types with the taxa: Ambulatory on land; pectoral oscillation in water Ambulatory on land; pelvic oscillation in water Undulatory on land; pelvic oscillation in water

Ambulatory on land; pectoral oscillation in water - Otariidae Ambulatory on land; pelvic oscillation in water - Odobenidae Undulatory on land; pelvic oscillation in water - phocidae

List one adaptation we see in deep diving marine mammals.

Any of the following: thick tissues around ears flexible ribs

Certain species of whale barnacles may infest only certain species of whales, a fact that paleontologists have exploited. What can fossil whale barnacles tell us about their whale hosts?

Barnacles that die and fall off the host whale will sink to the bottom of the ocean and become part of the fossil record. Since only certain species of barnacles attach to certain whale species, the species of fossil barnacles found in a certain location can help paleontologists retrace routes of the host whale species millions of years in the past based on where the fossils are found.

What is the Order in which living whales and dolphins are categorized?

Cetartiodactyla Artiodactyla

Exhibits one external blowhole Exhibits an asymmetric skull Exhibits telescoping of the skull

Exhibits one external blowhole- Odontoceti Exhibits an asymmetric skull- Odontoceti Exhibits telescoping of the skull- Both Odontoceti and Mysticeti

Large Odontocetes are not as energetically efficient as smaller ones. Why do they still benefit from being so large?

For odontoceti that grow to be really large, their biosonar organs grow at disproportionately faster rate. This means that the larger odontocetes have hyper-developed biosonar capabilities and larger bodies. This allows them to dive deep in ocean and track down hard to reach prey using their enhanced biosonar skills. Because their prey reside so deeply in the ocean, they are able to exploit the deep sea ecological niche space that no other predator can access. So even though the larger size is less energy efficient, being larger allows odontocetes to dive deeper which removes them from competition for prey closer to surface (this is a huge benefit).

Populations of large baleen whale species have been protected from hunting under international treaty for many decades, yet they still face many threats. Name four.

Four threats to baleen whales are: - Fishery bycatch - Entanglement in things like fishing nets - collisions with boats and ships - anthropogenic noise that interferes with whales ability to use their echolocation underwater and can damage hearing

Match the listed features with the most appropriate cetacean taxon. Includes the longest-lived species Includes the largest species Includes the species with longest known migratory route Includes the deepest diving species Includes the only known monogamous cetacean

Includes the longest-lived species - Balaenidae Includes the largest species - Balaenopteridae Includes the species with longest known migratory route - Eschrichtiidae Includes the deepest diving species - Ziphiidae Includes the only known monogamous cetacean - Pontoporiidae

Describe how the tectonically driven rearrangement of physical barriers may have contributed to the evolution and speciation of the mysticete whales. When did this happen? What geologic and oceanographic changes occurred? How did those forces shape the evolution and speciation of Mysticeti?

Plate tectonics opens and closes seaways. It has influenced the initial divergence of cetaceans during oligocene and diversification you see current day. Australia and South America were once connected to Antartica. As plates moved, it opened circumpolar current, large-scale ocean circulation patterns driven by plate tectonics. This drove density gradients in water from surface heat and flushes of fresh water and defined cetacean habitat and food distribution 35 million years ago. 20 million years ago connections of oceans at equator were closing off because South and North America crashed into each and closed off the Central American seaway. The Tethys sea was also closed as Africa collided into Asia. All of these seaways closing lead to the diversification of modern taxa as once connected seas were now separate and species were isolated, allowing them to evolve unique families.

The only fully aquatic herbivorous mammals are in the Order _____________.

Sirenia

The transition from a terrestrial to a fully aquatic existence in cetaceans is well-documented in the fossil record. How does the archaeocete fossil Maiacetus (pictured below) contribute to our understanding of cetacean evolution?

The beautifully preserved Maiacetus fossil shown above showed scientists that the fetuses of these animals came out head first. This adaptation in cetaceans meant that Maiacetus was likely coming on land to give birth, even though it did spend a lot of time in the water. Coming out head first allows the fetus to still breath as it is being birthed

Describe the integument (skin and fur) of the polar bear and discuss the adaptive benefits with respect to where this species lives.

The skin of the polar bear is very black which allows the skin to act as a heat insulator. It absorbs all sunlight energy being transmitted through clear transparent hairs, helping keep the polar bear warm in the cold arctic temperatures. The clear transparent hairs on the polar bear have hollow cores made of keratin that lack any pigment. The keratin structures have tiny light scattering particles so when the sun hits them, light gets trapped in hollow hair and bounces off all the tiny particles and salt accumulated on the skin. This allows them to appear white in the sunlight and camoflauge into the white snowy background of the arctic.

Why is marine mammal diversity concentrated in the coastal and polar areas of the world's oceans?

This is where upwelling occurs. When cold nutrient-rich water is uplifted from the bottom of the ocean and comes to the surface, it causes primary productivity to increase. This can feed some marine mammals and also cause blooms in the species they prey on, like fish, zooplankton, crustaceans, etc. Coastal and polar regions experience upwelling of nutrient rich waters, so they are hotspots for marine biodiversity, including marine mammals.

Give the taxonomic order to which the marine mammal represented by this skull belongs. Explain the functional significance of the large nasal opening and the delicate, scroll-shaped bones housed in it.

This nasal opening belongs to a sea otter which is part of the family mustelid and the order carnivora. The large nasal opening and the delicate scroll-shaped bones are to house soft nasal tissue and nerves in that area. These soft tissues and nerves serve to warmed cold air as it enters the nose before it hits the primary vessels inside the body. Before exhaling air, heat is captured and preserved in the body. This helps these otters conserve heat in cold waters.

The paper describes noise as an "ephemeral energetic pollutant." How does the impact of noise pollution compare to other forms of pollution, like plastics or greenhouse gas pollution? What solutions does the paper propose to combat noise pollution in oceans?

Unlike other forms of pollution, noise is not persistent. If we stop making the noise that is polluting the whales habitat, the noise goes away. Plastic and greenhouse gas dont just go away when you stop producing them, making noise pollution hopefully an easier conservation issue to tackle. If the noise is stopped, it will go away and animals can take advantage of freed up space for better communication. The paper suggests lowering ship speeds and adjusting ship technology to come up with solutions like engines that generate less sound. These solutions would hopefully have immediate ecological effects since this noise will not persist in the environment once it has stopped being generated.

Why did the authors use both genetic data and fossil data to construct their phylogeny? Describe one benefit and one drawback for each type of data.

Using both genetic and fossil best allowed the authors to construct their phylogeny. In this case, without one, the other did not seem to fully explain the evolutionary history of cetaceans. Early molecular studies showed a relationship between cetaceans and hippos, however since genetics are analyzed using statistics, the findings were not statistically sound enough to confidently confirm their relationship. Finally fossils were found that linked cetaceans to the order artiodactyls (fossils were found that were similar to whales but had arms and legs). This backed up the previously found molecular data saying whales and artiodactly were related by finding a key missing link in their ancestry. This finding demonstrated the importance of combining both genetic and fossil data to construct a phylogeny. Sometimes using genetics only or fossil record only doesn't do the trick. Molecular data alone showed there was some link between cetaceans and artiodactyla, however without fossil data it was unsure how closely related they were. As you analyze the genetics of smaller clades, its hard to find statistical agreeance, as we saw in figure 6, making it harder to confirm the closeness of relation. At first, fossil data alone did not show any relation between cetaceans and artiodactyls for a long time. So this made it difficult to guarantee and link between cetaceans and artiodactyls. Without the newfound fossil data, this could not be proven which is one issue with using fossils for phylogenies. Sometimes fossils are not discovered or lost in history, which can make it difficult to connect these groups. Without the missing link they found, it would have been difficult to confirm the relationship.

The correct binomen (species name) for the long-beaked common dolphin is: Delphinus Delphinus sp. Delphinus capensis capensis D. capensis

delphinus capensis (short beaked is delphinus delphus)

The closest living relatives to the sirenians are the _______

elephants

The stem pinnipedimorph Enaliarctos emlongi† is believed to have exhibited a polygynous mating system based on what evidence? recovered fossils of females outnumber males recovered fossils of males outnumber females evidence of sexual size dimorphism all living pinnipedimorphs are polygynous so their ancestors would have been polygynous as well

evidence of sexual size dimorphism

All polar bears will overwinter in dens. True False

false

River dolphins comprise a monophyletic group. True False

false

The diving reflex is unique to marine mammals. True False

false

True or False By international agreement, aboriginal subsistence hunters are limited in the number of whales they can kill annually as well as limited to taking whales in traditional (not modern) hunting methods.

false

true or false Baleen whales have plates of baleen attached only to the upper jaws; common dolphins and sperm whales have teeth attached to both their upper and lower jaws.

false

The flipper of a dolphin and the flipper of a sea lion are an example of: homoplasy synapomorphy homology

homoplasy

Match the trait or description with the most correct cetacean taxon. includes the oldest living cetaceans includes the most endangered species of living cetacean includes the only known serially monogamous species includes the deepest diving mammals

includes the oldest living cetaceans- Balaenidae includes the most endangered species of living cetacean- Phocoenidae includes the only known serially monogamous species- Pontoporiidae includes the deepest diving mammals- Ziphiidae

Harbor seals (Phoca vitulina) lack the extreme size sexual dimorphism common to many species of pinnipeds. The males tend to be only slightly larger than females, with average body lengths of 1.7 and 1.5 meters, respectively. Which of the following statements would you predict with respect to male harbor seals? male harbor seals have relatively large testes male harbor seals have relatively small bacula male harbor seals have relatively large bacula male harbor seals have relatively small testes

male harbor seals have relatively small bacula male harbor seals have relatively small testes

Identify which of the following are true of ambergris: is regurgitated by sperm whales may be found on beaches or floating in the sea may include undigested squid beaks within it has no commercial value in the 21st century may be recovered from the intestines of sperm whales was used in perfumes

may be found on beaches or floating in the sea may include undigested squid beaks within it may be recovered from the intestines of sperm whales was used in perfumes

The mammalian stapes is part of the: inner ear middle ear outer ear

middle ear

Match the taxon with its distribution. monk seals - leopard seal - Baikal seal -

monk seals - warm subtropical waters leopard seal - coast of Antarctica Baikal seal - freshwater lake

Choose whether each statement applies to Mysticetes, Odontocetes, or both. Expoits very abundant prey that is low on the food chain: [ Select ] ["Odontocetes", "Mysticetes", "Both"] Dives to depths of over 800 meters: [ Select ] ["Mysticetes", "Both", "Odontocetes"] Engages in multiple feeding events per dive: Both Uses biosonar to hunt large prey: [ Select ] ["Both", "Odontocetes", "Mysticetes"]

mysticetes odontocetes both odontocetes

The pinniped in this image is in the family

otariidae

Which of these tissue types does the paper identify as the most vulnerable to damage from hypoxia? (Check all that apply) Endocrine cells Renal tissue Myocardium Hepatic tissue Neurons

renal tissue myocardium neurons

Identify the preferred prey of these ETP (eastern tropical Pacific) killer whale ecotypes: primarily salmon primarily marine mammals sharks and other large fish

resident killer whales transient offshore

Your friend, Jaime, is an amateur naturalist who likes to collect bones. They bought part of an unknown marine mammal skeleton on eBay from someone in Japan. Jaime hoped the bones might be from a walrus but was not sure since walruses don't occur in Japan. Knowing that you took a course in marine mammals, Jaime emails you an image of the relevant page from their field notebook and asks if you could help identify the specimen. You gladly reply (first telling Jaime it's illegal to buy marine mammals parts, of course) that the bones are from a [_________] . As a bonus you tell Jaime the animal's primary diet, which would have been [_________]

walrus clams