Marine Bio Exam 3

Polar Bears: How well do they tolerate other bears? What is the biggest contributor to population decline?

Tolerate other bears when food is plentiful or when they're desperate because they don't want to waste energy on each other. Half polar bear populations in decline, biggest threat likely climate change (changing sea ice).

Phocids: Walrus are found where? What are their two predators? Are adults capable of defending themselves?

Arctic coasts and ice floes; predators are polar bears, orcas 🡪 adults can fatally injure polar bears, calves vulnerable

Polar Bears: What is their eyesight like in air and water? What enables them to have a great sense of smell? (2) What are the two things that they're capable of smelling?

Good visual acuity in air but likely very little in water based on eye morphology Have large surface areas in their nasal tubes, covered with olfactory sensory epithelium: - Most sensitive nose of any mammal 🡪 can smell seals 30 km away and through several meters of snow. The odor of sebaceous waxy secretions and milk from lactation.

Sea Otters: What are the two kinds of habitat that you would find them in?

Habitat often kelp forest (narrow strip offshore), shallow estuaries where they can find food, shelter

What are the 2 things credited with Sirenian recovery?

Habitat restoration, boat speed restrictions credited with species recovery.

Pinnipeds: Why do they haul out when they molt? What is something they can't do while they're molting and what happens while molting? What process do we associate the hormonal changes essential for molting with?

Hauling out required 🡪 need to maximize skin temperature for hair re-growth; can't forage 🡪 lose considerable weight while molting Hormonal changes associated with molting may play role in re-activating embryo -> involves lowering of metabolic rate in females.

Sea Otters: 75% of foraging trips successful 🡪 females spend nearly 50% of time foraging 🡪 why?

High metabolic rate (no blubber to keep warm, just fur) 🡪 high calorie requirements, more in winter, mothers nursing pups -> have to consume 20-25% of body weight daily

What is the number one threat to Sirenians? Why is that the case? (2)

Human activities (mainly boat strikes) account for third to half of all deaths (record high 2016) Can definitely hear boats, so localization may be issue 🡪 can't detect phase cues due to head morphology? They move slowly in response to what they hear - it's probably a lack of an ability to process that information quickly enough.

Sea Otters: What are the 4 things that are setbacks for Sea Otter recovery?

Hunted for their dense fur. 1913 sea otter became one of first marine mammals protected by state law; recovery of CA populations has been slow Setbacks include El Nino (lack of upwelling decreases kelp growth), gill net fishing (competition with humans for same foods), oil spills, disease

Phocids: How do Monk Seals differ from all other Phocids?

Monk Seals are the only tropical seals whereas the rest of Phocids are all ice breeding or pack ice. Pinnipeds tend to take up space on beaches and so that's why Phocids are found on ice mainly except Monk Seals.

Phocids: What is unique about Monk Seals' molting?

They do catastrophic molting.

Phocids: Do Walrus have sexual dimorphism?

They have sexual dimorphism, males have bigger tusks and are larger.

Phocids: What are tusks used for? (3) What is it reflective of?

Tusks used in dominance, hauling out on ice (used as a pick pick), for defense, as secondary sexual characteristics in males (females have smaller tusks). This is reflective of dimorphism - bigger tusks are more likely a sexually selected trait for males. Both sexes do have tusks which are used in defense from polar bears and an extra hand as a ice pick to haul out onto the ice. Major predators are predominantly polar bears who will go for the young ones. Extremely thick skin is hard to pierce and the tusks can inflict fatal wounds.

What purpose does vocalizations serve for Sirenians? What is their eyesight like and what conditions does it work well under? Also what time of day are they active and why?

Underwater sounds they make likely social since prey are plants ☺, few predators (killer whales, sharks, gators/crocs) Likely farsighted but function well under low light, murky conditions 🡪 typical of their habitat Often active at night especially in areas where they were once hunted.

What describes the sensory system of Sirenians? What explains why that is?

Use very mobile lips, vibrissae (like whiskers) to gather vegetation, like cow. Rely on vibrissae to find appropriate food since they cannot see directly in front of them.

Polar Bears: Why will they sometimes hold one of their feet up? What do they after a dive?

Very efficient at keeping heat with low surface to volume ratio. A polar bear will have one of their feet held up in order to thermoregulate in order to keep their feet off of a cold surface. They will also roll around on the snow after a dive to get the salt off of them to retain their ability to thermoregulate.

Sea Otters: What kind of breeding system do we see? Why is that?

We mainly see scramble competition as not all females are ready for breeding at the same time - there is a lot of sperm competition and not a lot of dimorphism.

PInnipeds: Length of delayed implantation depends on what? (2).

length of delayed implantation depends on lactation period. Gestation period mainly scales to body size.

Pinnipeds: What is the critical information gathering apparatus for all pinnipeds? What is it analogus to in terms of neural sensitivity?

pinnipeds have sensitive tactile vibrissae around lips, cheeks 🡪 used to locate prey 🡪 critical information-gathering apparatus for all pinnipeds neural sensitivity similar to primate hands.

Pinnipeds: How are Pinnipeds able to compensate for changes in pressure underwater and what is the drawback? What's the term for that drawback?

pinnipeds have strong lens to compensate for changes in pressure underwater -> means they are more myopic (or near-sighted) in air. They have a spherical lens which resists the changes that occur as a result of pressure. They have pretty good vision underwater however once you release that pressure, their eyes bulge out and so they are nearsighted in air. Myopic.

Phocids: Monk Seals have reverse dimorphism - what is that reflective of?

reverse dimorphism - the females are larger than the males. This is a reflection of their increased energy investment in offspring and males do compete for females and territory.

What is the source of microbes for hindgut fermentation?

source of microbes for hind gut fermentation likely coprophagy (eating feces) 🡪 has been observed in wild, not sure how common

Phocids: When do Phocids mate?

- Phocids mate after they wean their baby, they're not ready to mate until they finish nursing their offspring. This is a range subject to variation. Male has to wait for female then she's ready to mate.

Pinnipeds: What is used to synchronize reproductive cycles? What is also another factor that influences reproductive cycles and how does it affect their behavior? what kind of species is it absent for?

- Photoperiod likely used to synchronize reproductive cycles - Cues (such as seasonal nature of prey availability) largely absent in tropical species 🡪 reproduction often spread over several months, food supply more important.

What are the 3 species that have gone back to the water?

3 species that have gone back to the water: polar bears, sea otters (mustelid) and pinnipeds.

Sea Otters: What does the female do for the pup and why? (2) What allows the pup and female recognize each other?

5-15% time budget spent grooming 🡪 coat fur with waterproofing secretions; rolling, tumbling at surface, blow air into fur to replenish air layer. Pups can't groom selves, much of mom's surface time spent grooming them so they're waterproof when left at surface. Pups nursed, brought food by mother; in constant contact at surface, very close bond; communicate vocally may learn each other's voices.

Pinniped: What does the absence of a dedicated dual system for air and water indicate? Where do seals and walrus spend most of their time? Where do sea lions and fur seals spend most of their time?

Absence of dedicated dual systems for use in water, air, must be compromises in function - it's a tradeoff as you can't be dedicated to both. All pinnipeds have excellent underwater hearing; difference in air not as marked as previously thought for seals, walrus. They still hear pretty well in air. 🡪 spend most of their life at sea. Sea lions, fur seals hear nearly equally well in both media, slight edge to air 🡪 spend much more time on land than seals.

Phocids: What impacts adult mortality for Elephant Seals? (2) What impacts pup mortality? (2) How does climate change threaten elephant seals?

Adult mortality: predators such as white sharks, killer whales, starvation (El Nino); pups drown in storms, get crushed by males fighting (highest source of mortality). Cessation of hunting 🡪 both species' populations rebounded to near historic levels. Climate change threatens elephant seals as they spend a lot of time at sea so they are subject to water temperature changes and so forth.

Polar Bears: What are the mating strategies for them? (2) When do polar bears come together?

Adults come together to breed, otherwise solitary; adult males may kill cubs. Polar bears use scramble competition and use mate guarding in order to protect a female that is in their reach.

Polar Bears: If cubs are altricial, what does that imply? What happens to half of the female's weight when they're hibernating?

Altricial young also means that if she loses one early on, hasn't invested too much energy. Female loses half her body weight, converting fat stores to milk for cubs, in den for months. They nurse until they grow big enough to leave the den.

Pinnipeds: Describe what impact an amphibious lifestyle will have on how Pinnipeds reproduce. Is reproduction synchonrous or not? What led to it?

Amphibious lifestyle 🡪 reproductive habitat completely separate from foraging habitat, seasonal nature of prey availability (wide range as well) 🡪 likely led to synchronous reproduction in most species

Which of the following is NOT true of delayed implantation? A) Occurs when fertilized embryo enters a state of extremely slow development until further development is triggered after a prescribed period of time B) Females store sperm after mating to fertilize their eggs at a later time C) Is often used to synchronize birth with favorable environmental conditions D) Can be triggered by suckling of offspring in marsupials and rodents E) All of the above are true

B

Polar Bears: When do they breed? When does delayed implantation end?

Breed in spring when females with 2 year old cubs (or no cubs) come into estrus 🡪 delayed implantation ends when females enter winter dens late September

Phocids: Where do Phocids breed? (2)

Breed on either ice (pack ice, floes) or land (mainland or island beaches, rocky shores)

What exactly do Sirenian calves learn? How do Sirenians greet one another?

Calves form close bonds with mothers 🡪 offspring may learn best foraging sites from her, other important info. Individuals encountering each other in common waterways often greet one another with nuzzling, rubbing and/or kissing -> clearly social but function unknown

Phocids: Since Phocid females are clumped, what becomes a viable mating strategy? (2) Species that give birth on beach will mate where and what species is the exception? Species that give birth on the ice will mate where?

Clumped distribution favors female or resource defense; male strategy also depends on where mating occurs: Species which give birth on beach 🡪 mate on beach (harbor seals weird exception); species which give birth on ice -> mate in the water.

Phocids: How does clumped female distribution affect selection for pup recognition? How are pups' identity confirmed? (2)

Clumped female distribution 🡪 strong selection for recognition to avoid feeding wrong pup. Pups produce individually-distinctive isolation/distress calls (frequency-modulated narrow-band calls) when separated from mom. Mothers produce distinctive pup attraction calls when separated 🡪 pups recognize mother's voice; pup identity confirmed by olfaction.

Sea Otters: What do they use to open prey shells? (2) Also what is the unique physical trait that allows them to store food or tools?

Crushing molars, use tools to help break open prey shells 🡪 select stone, use as anvil on chest or as hammer Pouches used to hold food or tools while swimming 🡪 most otters use left pouch, leaving right forelimb free.

Polar Bears: What are cubs like when they are first born? What does the female do? Why do they not breed all the time? What limits them? (3)

Cubs born blind, helpless (altricial) in dens while female hibernates (much like other bears). Energetic demands mean females only breed every 3-4 years; rate limited by food availability 🡪 may need to forage over great distances, endure periods of starvation.

Phocids: What allows Elephant Seals to hunt at deep depths? How do we know that they even hunt so deep?

Deep-sea rhodopsin (visual pigment) in their cones lets them detect bioluminescent deep-sea prey 🡪 cookie cutter shark bites confirm foraging at depths -> 900 m.

Sea Otters: What determines what a pup will eat for the rest of their life?

Different otters have 'specialty' prey 🡪 offspring taught to hunt, inherit mother's preference 🡪 culture! Mothers wrap themselves, pups in kelp fronds to keep from drifting, use sheltered coves if no kelp.

Sea Otters: What do they use to locate prey?

Dive, bring prey to surface; sensitive tactile vibrissae around lips, cheeks used to locate prey.

Phocids: What is Walrus diet? What describes how they feed?

Eat mostly benthic invertebrates, especially bivalves like clams; will eat carrion like anything that is dead, observed killing small seals, seabirds 🡪 not clear how often Suction feeders 🡪 muscular tongue creates vacuum strong enough to suck bivalves from their shells.

Sea Otters: What is delayed implantation and its two types?

Embryonic diapause (2 forms): Seasonal delayed implantation Lactational delayed implantation

Sea Otters: What is their mating behavior made up of? (3).

Estrus can last for 2 weeks; mating behavior includes single male to female nuzzling, grooming each other, twirling, tumbling at surface.

Sea Otters: What is estrus?

Estrus is mating reception window - window for mating and getting pregnant. Narrow period of time for a male to find a female to mate within that 2 week window. A lot of males are competing for access to females. Lots of pushing, shoving and sperm competition.

Phocids: What are the 2 main conservation efforts being undertaken to help Monk Seals?

Extensive education, new national monuments, marine reserves off big island increasing food levels, protect breeding grounds Programs like "Project Head Start" target female pups, provision as necessary, transport to less impacted habitats so that they can reach sexual maturity and breed. Populations on northwest islands continuing to decline; big island, Oa'hu population increasing -> seals may be habituating to human presence.

Pinniped: How do Pinnipeds overcome being myopic/nearsighted in air? What are the two limitations for this adaptation?

Extreme pupil constriction helps overcome this (being myopic/nearsighted) in air 🡪 similar to a pinhole camera which has infinite depth of field. - allows focusing at varying distances to maintain visual acuity (depth perception compromised, but they can't tell how far away things are.) Works in bright light, as long as pupil doesn't dilate beyond this area -> acuity declines in dim light. Drawback summary: does not work well in dim light and depth perception is compromised as they cannot tell tell how far away things are.

Family Odobenidae: associated with what? Family Otariidae: associated with what? Family Phocidae: associated with what?

Family Odobenidae: walrus Family Otariidae: sea lions, fur seals Family Phocidae: true seals

Phocids: What is female distribution based on? (3)

Female distribution based on availability of birthing sites, predation pressure, food - Beaches are limited 🡪 fewer choices -> clumped.

Phocids: Where describes the breeding system of Walrus? (2)

Females cluster at edge of pack ice 🡪 several males attend each female herd; females may mate with males as they come and go Males perform ritualized visual, acoustic displays underwater and in air = Lekking

Phocids: The best birthing sites are found where in a group for Elephant Seal Females? Where are the worse and what is the drawback?

Females compete for best birthing sites in center of group, lower ranking females on edges (more likely harassed by sneaker males)

Sea Otters: What are the two ways that females give birth? Are babies born knowing how to swim?

Females give birth floating on back or on land, twins rare. Babies need to learn how to swim.

Phocids: When do Elephant Male Sneakers intervene?

Females may use water earlier to cool off as necessary 🡪 sneakers sneak when the females are cooling off on the beach.

Phocids: When are Elephant Seal Females ready to mate? Do females mate every year? What happens to pups if there isn't enough food? (2)

Females nurse pups, then wean them, mate, return to sea to forage. Females lose 30-40% of body weight, often skip breeding during El Nino because breeding is so energy intensive and they need to feed for themselves. They will delay breeding or they may abandon pups early because they don't have enough to eat.

Phocids: What do Elephant Seal females do when a male approaches them that they do not approve of? What is the benefit of mating with multiple males?

Females vocalize loudly to reject male's advances 🡪 calls recruit territory holder (the dominant male) to run off intruder Females often mate with multiple males 🡪 selection for sperm competition and/or mechanism whereby females can choose which male fertilizes her offspring. This is a form of internal control - the ability to hold sperm as packets and choose which one fertilizes their egg.

What are the teeth of Sirenians like? What is it the result of?

Front teeth constantly being eroded 🡪 replaced by back teeth. Likely result of grinding large amounts of grass, high silica content makes it abrasive -> adaptation also seen in elephants.

Phocids: In the arctic, do females scatter or clump up? Knowing the answer to that, what two mating strategies have become viable?

Ice is plentiful but unstable 🡪 too many pups attracts unwanted attention from polar bears 🡪 females scattered. Water mating + scattered females which makes resource defense and female defense as non-viable strategies 🡪 mate guarding, lekking.

Sea Otters: What is lactational delayed implantation? Why is it useful?

Lactational delayed implantation used in rodents, marsupials 🡪 suckling of offspring causes new embryos (blastocyst stage) to enter diapause. You can be pregnant and be nursing at the same time - the nursing can delay implantation. You focus your energy investment on offspring and once that is done then embryo is then allowed to be implanted.

Sea Otters: Do they have dimorphism? What are the 4 things that they do for most of the day?

Largest mustelid, smallest marine mammal; long rudder-like tail, no real dimorphism (males slightly larger than females) Most time spent: floating on surface (lung air = buoyancy), foraging (morning/evening), sleeping (mid-day), grooming

Phocids: Who is the intended recipient of Walrus lekking?

Likely both intrasexual (competition between members of same sex) and intersexual selection (competition between members of different sexes or mate choice). Lekking can be used to repel rivals and attract mates.

Do Sirenians exhibit any kind of dimorphism and if so what kind? What do males participate in every year and what purpose does it serve?

Little dimorphism; male dugongs have small tusks 🡪 likely secondary sexual characteristic, older females sometimes have them too; none in manatees Males participate in 'cavorting' herds year-round (last few hours) = intense pushing, genital contact, homosexual behavior 🡪 may determine dominance in mating; tusks often leave scars

What is the digestion system of Sirenians similar to?

Longer intestinal tract than other marine mammals, similar to non-ruminating herbivores (~ 20 m large intestine)

Phocids: Which is the longest for Walrus? Their gestation or implantation period? What is unique about how Walrus calves and mothers interact?

Longest pinniped gestation (shorter delayed implantation); females nurse offspring more than year (solids after ~ 5 months). Calves accompany mothers to sea, nurse in water -> other pinnipeds don't do this.

Phocids: What are the two biggest threats to Monk Seals? (2)

Loss of beaches through erosion, human activity (avoid crowds, boats) Over-fishing 🡪 loss of food for Monk seals as they are competing with humans, get tangled in fishing gear.

What helps Sirenians digest their food and what function does it serve?

Lots of microbe fermentation 🡪 important site of nutrient absorption

Pinniped: What is tapetum used for? When is it used? How does it work? (2) What does having more cell layers mean?

Low light conditions underwater 🡪 most marine mammals have tapetum to harvest light: layer behind retina reflects photons not absorbed by visual pigments, allows second chance at photons. - Pinniped tapetum equal to or more reflective than that of terrestrial predators; more cell layers = higher reflectance.

Phocids: Monk Seals have a biased sex ratio towards which sex? What has this biased sex ratio led to? Also what is the impact of male rivalry on females? Do females fast while nursing pups?

Male biased sex ratio 🡪 increased competition (resource defense, prefer beaches/caves) Females being injured by competing males, dying from infected wounds. Females fast while nursing pups on beach.

Sea Otters: Where do males bite females and where does the behavior originate? Why might they do that?

Male often bites female on face, especially nose 🡪 mating can last for up to 30 minutes in water; biting likely hold-over of carnivore phylogenetic history (many other carnivores include neck bite as part of copulation behavior) Possibly damaging neck fur reduces fitness too much so this behavior moved to face? Since fur plays such a big role in thermoregulation.

Phocids: Elephant Seal Males or females arrive first? Do they fast during breeding and what does that result in? What is the outcome for males who don't hold territory? (2)

Males arrive first to set up territories 🡪 females arrive few weeks later, give birth (single pup, twins very rare); both fast during breeding so there is increased mortality and it's very difficult to hold territory for a long time. The only outcome for males that do not hold territory is that they don't breed at all or they become sneaker males.

Phocids: Do Elephant Seals have sexual dimorphism? What are male Elephant seals known for and what does it do as well as what is it an indicator of? What does a low pitch vocalization mean?

Males known for distinctive inflatable proboscis (nose) which acts as an amplifier to help make their vocalizations travel further which allows them to use as an honest indicator of how big they are a low pitch vocalization implies strength to rivals, large chest shield which is a bony plate reinforced by connective tissue so that when they do get hit then they receive less damage. They have sexual dimorphism.

Phocids: What level of parental care do both parents provide? What is the male mating strategy dependent on?

Males provide no parental care 🡪 polygynous 🡪 male strategy dependent on female distribution

Sea Otters: What is the main breeding strategy for males? What does it indicate about the male? What happens if they can't pursue the main breeding strategy?

Males set up territories around females in estrus (overlapping their home ranges, but smaller) Regions with high food density support higher densities 🡪 become saturated, males that can't hold territories excluded. Males with high quality territories (i.e. better foraging opportunities) attract more females (resource defense polygyny) 🡪 seems fluid rather than fixed mating system ------------- Males will defend a physical space which tend to have a lot of food which will attract females - the pups are dependent on mother for 8-9 months. If males can't hold territory, they mate with foraging females.

Sirenians are associated with what animal? (2)

Manatees and Dugongs.

What feeding strategy characterizes Manatees? What feeding strategy characterizes Dugongs? How deep do they dive?

Manatees are opportunistic, mainly surface feeders. Dugongs mainly seagrass specialists, forage on bottom of shallow bays, inlets. Both spend much of time near surface, sleeping, foraging -> shallow divers.

Phocids: What is the breeding system of Monk Seals?

Monk Seals practice resource defense polygnony - females are choosing males based on the quality of the male and his actual territory. Female elephant seals are focused on finding a good quality male and a good place on the beach to give birth - elephant seals don't care much about the physical space in the same sense.

How do marine mammals produce sound? (3 steps)

Most mammals produce sound by moving air through larynx, vibrating vocal chords 🡪 sound modified by tongue, teeth, nasal passages

Pinniped: Why do marine mammals have multiple photo-pigments? (2)

Most marine mammals have multiple photo-pigments 🡪 evidence suggests color vision NOT primary reason. To maximize contrast so they can see prey coming from the side or if they're below the prey then they need contrast from a lighter background.

Pinniped: How do they produce sound? (3) What is a unique physical feature that Otariids and Walrus have for making sound?

Most produce sound by moving air through larynx, vibrating vocal chords like we do 🡪 sound modified by tongue, teeth, nasal passages Pharyngeal pouches found in otariids, male walruses are another source of sound.

Sea Otters: What are the two things that their eyes can do?

Most spectacular visual range of any vertebrate: sees well in both air, water: Can change radius of curvature (and strength) of lens Redistributes aqueous humor of eye to move lens forward, reinforce it to compensate for pressure change underwater. This is also used with alveolar collapse when they dive really deep.

Phocids: How are Elephant Seal pups different from Sea Otter pups when they are newly weaned?

Newly weaned pups ('weaners' or 'weanlings') group together on beach, learn to swim in shallow water away from nursing females and aggressive males. Mother elephant seals will learn their pup's voice and vice versa for the pup. Vocal and olfactory recognition. Unlike sea otters, they have to learn a great deal on their own.

What describes the mating system of Sirenians? (2)

No monogamy, more like scramble competition or promosciousity as in males will breed any available females. Male biased scramble competition. Mating herds form in summer: one receptive female, up to 22 males jockeying for position for 3-4 weeks (scramble competition) Female may choose to mate with multiple males, not clear if sperm competition plays role.

Sea Otters: Why might females not reproduce every year? What is the impact of raising a pup on the mother? (2)

Otters can reproduce annually, energetic demand of pups on mothers means females don't reproduce every year: High metabolic rate, plus cost of provisioning, caring for pups implicated in increased mortality of females near end of lactation period along central CA coast. They don't abandon their pup and go all in - they end up exhausting and starving themselves to death. Thometz et al. (2014) quantified energetic demands associated with pup rearing, concluded female otters exceptionally vulnerable to energetic shortfalls.

Sea Otters: What has caused Sea Otters to lose 25% of genetic diversity? Why are oill spills an issue for Sea Otters?

Otters have lost approximately 25% of genetic diversity due to bottleneck 🡪 now ~ 3k CA otters (formerly ~ 100k) Oil spills like Exxon Valdez (killed ~ 5k otters) are huge risks due to impact of oil on fur's ability to thermoregulate Poaching: rehabilitated otter from MBA's recovery program found shot in Morro Bay September 2017; another found skinned near Monterey Bay; 3 shot August 2016.

Pinniped: What species have pharyngeal pouches and what species don't?

Pharyngeal pouches found in otariids, male walruses are another source of sound. Phocids have no pharyngeal pouches 🡪 not clear how underwater sounds are produced.

Pinniped: Vocalizations are most associated with what? What are the two components of pinniped vocalizations? What is the relationship between body size and frequency - why is this significant?

Pinnipeds vary in vocal repertoires: grunts, growls, barks, even some warbles, whistles. Vocalizations vary by age, sex, time of year, air vs. water 🡪 most associated with breeding. - some seals produce infrasonic seismic vibrations in air (e.g. male northern elephant seals). Very low frequency components and infrasound components - the lower the frequency, the bigger the animal and this can be used to scare off male rivals. - barks of California sea lions individually distinctive in air.

Pinnipeds: What pups do before they go to the sea?

Pups molt birth coats before going to sea

Sea Otters: Why might rafts be formed by females with pups? (2). How do Sea Otters keep from drifting away when they sleep?

Rafts of females with pups exist, adults much less social 🡪 not really sure why female rafts form 🡪 information exchange about foraging, dilution effect especially if you're together. Mothers, pups, even males hold each other's paws to keep from drifting while they sleep. They don't have to be related to do this.

Phocids: What is the process of repelling rivals for Elephant Seals? (2)

Repelling rivals begins with 'face-off': aligning head, body directly at rival if that fails 🡪 rearing up on front flippers shows off chest shield, open mouth displays canines, individually-distinctive 'clap-threat' vocalization (proboscis acts as resonator) > 70% conflicts resolved with vocal display alone without needing to fight.

What describes the speed of reproduction for Sirenians? Where do they give birth?

Reproduce slowly 🡪 females breed every 2-3 years, single offspring (twins do occur) Females seek sheltered shallow water to give birth, young nurse for 1-2 years 🡪 they do begin eating plant material soon after birth

Rods do what? Cones do what? What is the benefit of having both?

Rods maximize light sensitivity at depth to see prey approaching from below. Cones maximize contrast at shallower depths to see prey approaching from side. Having both allows wide range of conditions under which they see well, allows for large changes in light intensity between depth and surface.

Sea Otters: What are rafts? What purpose do they serve?

Scramble competition by males may be more normal, depending on prey densities. Non-breeding males aggregate into floating social groups = 'rafts' in less optimal habitats; synchronized behavior patterns in raft; play fighting -> Younger males are practicing adult behavior when it is lower stakes, and it may help establish dominance relationships between males for mates or food.

Sea Otters: What is meant by them being a keystone species? Explain in depth what happens when they are present and when they are absent.

Sea otters are keystone species in every environment that they are in. They are consuming the primary consumers who are eating the kelp and ensuring that the primary consumer population is under control. When prey populations are held under control, primary producers are allowed to flourish and so you get increased biodiversity. Kelp is a foundation species that creates homes for other species - kelp provides both food and shelter. When you remove sea otters, you see a huge drop in biodiversity which demonstrates how they are a keystone species essential for biodiversity.

Sea Otters: What are the two benefits of having the densest fur coat? What is its drawback? How do they maintain its effectiveness? When do they do it and why?

Sea otters have the densest fur coat - keeping air layer intact and reducing drag. Spend a lot of time grooming and coating their paws with waxy secretion then using it onto their fur to waterproof it. They do this after every dive. Process of diving disrupts the air layer so they have to reapply the waxy secretion every time.

Sea Otters: How is seasonal delayed implantation used?

Seasonal delayed implantation used to synchronize birth with more favorable environmental conditions 🡪 mustelids, ursids, pinnipeds (blastocyst may grow slowly in some, not 100% 'paused').

Pinnipeds: Milk is high in what? What happens to females after they give birth?

Single precocial offspring born on land (islands, beaches) or floating ice 🡪 like polar bears, pinniped milk high in fat (average is 40%) Females enter estrus postpartum - meaning after they give birth, they enter estrus.

Polar Bears: How do they typically hunt? When must they swim? Also, what frequencies is their hearing sensitive to?

Strong swimmers but don't hunt underwater, typically hunt on land 🡪 must swim between ice floes in summer Likely have good hearing with sensitivity to low frequencies 🡪 may also be sensitive to higher frequencies used by prey and cubs.

Pinnipeds: Synchronized reproduction is facilitated by?

Synchronized reproduction facilitated by delayed implantation

Sea Otters: What is their way of avoiding predators? Why are pups especially so vulnerable?

White sharks (CA), killer whales (Alaska) 🡪 only way to avoid predators appears to be diving; pups can't dive to avoid bald eagles (Alaska) -> pups are too buoyant!

Pinnipeds: Where do fur seals molt and how do they molt? What species does catastrophic molt? What gets taken out when they molt? When is molting quicker? How is the process driven?

fur seals molt continuously, most haul out on land for annual molt Only Elephant seals go through 'catastrophic' molt 🡪 shed skin, hair in big patches. Mercury and other contaminants in their skin and fur can be molted. Molting is quicker when skin is dry so that's why they are on the beach, and it is a hormonally driven process.