Pinnipeds

Question 1

What defines a pinniped?

Answer 1

Eight defining synapomorphies e.g. Distinguishing features

Question 2

What are the 8 features?

Answer 2

Large infraorbital foremen
Maxilla makes significant contribution to the orbital wall
Lacrimal fused or absent
Greater and lesser humeral tuberosities enlarged
Deltopectoral crest of humerus strongly developed
Short robust humerus
Digit I on hand emphasised
Digits 1 and V on foot emphasised

Question 3

What is a pinniped?

Answer 3

Members of the order Carnivora.
3 families ( orariidae, odobenidae, phocidae)
Compromises - 28% of marine mammals
33 different species
Estimated 50 million individuals

Question 4

Examples of otariidae (eared seals)

Answer 4

California sea lion
Galapagos fur sea

Question 5

Example of odobenidae

Answer 5

The only species is the walrus

Question 6

Phocidae

Answer 6

90% of all pinnipeds
The true seals or earless seals

Question 7

Evolution of pinnipeds

Answer 7

One hypothesis suggests that pinnipeds are diphyletic ( defendant from 2 ancestral lines) with walruses and orariids sharing a recent common ancestor with bears and phocids sharing one with muskeloidea. However genetic evidence suggest it is nonsense

The evolutionary link to terrestrial mammals was unknown until puijila darwini was discovered in 2007.

Question 8

Locomotion in pinnipeds

Answer 8

Both terrestrial and aquatic locomotion

The three distinct patterns of pinnipeds swimming are recognised yet all create thrust with the hydrofoil surface of their flippers

When swimming these hydrofoils orientated at an angle to the direction of travel, producing thrust parallel to the direction of travel and generating lift perpendicular to the direction

Question 9

Locomotion in otariids

Answer 9

Less adapted to the aquatic lifestyle since they are primarily breed on land and hall, lamp, more frequently than phocids

They have proportionately much larger foreflippers and pectoral muscles and have the ability to turn the hind limbs forward and walk on all fours

They have extensive movements of the head and neck occurs in terrestrial locomotion

The swimming power derived from the use of flippers more than the whole body movements 

Question 10

Locomotion in phocids

Answer 10

Swim by sideways movements of their bodies using their hind flippers, whilst foreflippersare used for steering

Hind flippers are also bound to the pelvis in such a way that they cannot bring themunder their bodies to walk on them = clumsy

Question 11

Thermoregulation in pinnipeds

Answer 11

Blubber is the main insulating tissue

Blubber is also an energy store and used for buoyancy

Blubber is penetrated by vascular beds so heat loss can be controlled via counter current heat exchange

Lower thickness changes in response to environmental temperatures

New seal pups do not have blubber, but do have thick layers of hair and higher rates of metabolism

Question 12

Osmoregulation of pinnipeds

Answer 12

Due to inhibiting marine environment, the animals internal fluid composition differs from the external environment

marine mammals consume water rich fish and marine invertebrates, which are composed of 70 to 80% water as well as electrolytes and nitrogen

They gain water from metabolise in food and blubber and they also lose water through evaporation, excretion and respiration

Question 13

Metabolic water

Answer 13

1.07g of water is generated for every gram of fat oxidised

0.56g of water per gram of carbs

0.39g of water per gram of protein

Question 14

Three types of vibrissae (whiskers)

Answer 14

Rhinal
Superciliary
Mystical

Question 15

What are mystacial whiskers?

Answer 15

Arranged in rows on either side of of the nose
Either smooth (O family) or beaded (p family)

Embedded in the upper lip- highly innervated or vascularised

Functional significance for prey location

Question 16

What are superciliary whiskers?

Answer 16

Located above the eyes

Question 17

What are rhinal whiskers?

Answer 17

Located on top of the shout

Question 18

Diving adaptations in pinnipeds

Answer 18

Before diving, pinnipeds exhale to empty the lungs of half the air before closing their nostrils and throat cartilages to protect the trachea

The lungs have airways that are reinforced with cartilaginous rings and smooth muscles, and the alveoli that can completely deflate during deep dives. Can you please can also reinflate the lungs even after complete respiratory collapse.

The heart is moderately flattened to allow the lungs to deflate this way

The middle ear contain sinuses that appear to fill with blood prevent ear squeeze

Question 19

Diving adaptations- deep dives in pinnipeds

Answer 19

Any remaining air in their bodies is stored in the bronchioles and trachea, which prevents them from experiencing decompression sickness, oxygen, toxicity, and nitrogen narcosis

Pinnipeds of high amount of haemoglobin and myoglobin, stored in their bodies and muscles . Deep dive in species have blood volume is that represent up to 20% of their body weight.

When diving they reduce their heart rate and maintain blood flow to only the heart, brain and lungs

Question 20

Pinnipeds as predators?

Answer 20

They have similar ‘torpedo shaped’ bodies- which are awkward on land, but graceful in water

Visual predators that also have sensitive whiskers can help them detect pray

Most are generalist and opportunistic feeders, which is dependent on the seasonal variation and pray density

They may hunt solitary or cooperatively, but they don’t have echolocation

Question 21

Toothed whales (schusterman et al 2000)

Answer 21

Toothed whales evolved a highly advanced system of active biosonar

An echo location system is unlikely to have involved in pinnipeds, choose to the constraints imposed by the obligate amphibious functioning of the pinnipeds auditory system. As a result, these constraints, constraints have not developed highly acute, aquatic, high frequency, sound production of reception systems

However, pinnipeds have evolved enhanced visual, tactile and passive listening skills

Question 22

Phocidae as predators

Answer 22

Deep drivers = benthic ( bottom feeders)
Females fast during lactation

Question 23

Otariidae as predators

Answer 23

Shallow diverse with generations of 2 to 3 minutes and feed, mostly on fish in near shore waters
Females forage during lactation

Question 24

Prey size depends on how they eat their foods

Answer 24

Small fishes under 30cm long are consumed whole underwater
Large fishes above 30 cm long are bought to the surface, shaken violently and reduced to chunks that are swallowed piece by piece

Question 25

Foraging behaviour in crabeater seals

Answer 25

Feeds on krill, which it catches in large, quantities and strains from the water through its multicusped cheek teeth

Young crabeater seals experience significant predation by leopard seals

Question 26

Leopard seal foraging behaviour

Answer 26

Feed on diverse pray including krill, cephalopods, crustaceans, penguins, and other seals

Pray catch it depends on age

Seasonal feeders-
Krill is eaten from September to March
Penguins are eaten from January to March
Fur seal pups are eaten from November to February

Question 27

Three methods used for catching fur seal

Answer 27

Stalking
Rapid approach with wave
Open hunting

Question 28

what is stalking?

Answer 28

The leopard seals swam into the cove with his body submerged, exposing only its nostrils to breathe, where it waited at the edge of the pool or slowly cruised along the beach, and suddenly lunged at pups, approached it

Question 29

What is rapid approach with wave?

Answer 29

The leopard seal rode a swell towards the beach, swimming rapidly and lunged at pups on the beach

Question 30

What is open hunting?

Answer 30

The leopard seal made no attempt to hide itself, entered a shallow intertidal pool at high tide and lunged that pups

Question 31

Foraging behaviour of walrus

Answer 31

Feeds, primarily on three genera of bivalve molluscs
Foragers in shallow coastal waters- 70 m deep
Bivalves on the sea bottom are examined and sorted by the lips and whiskers before being sucked out and swallowed whole

Question 32

Pinnipeds as prey

Answer 32

The young spend more time close to shore, where they are circled by their mothers so predators can find them more predictably

An adult pillow, I would have to consume 2 to 3 pots per day or one adult female every 2 to 3 days

Question 33

What is a cost benefit approach?

Answer 33

Behaviour that is a shame to have an adaptive advantage so is favoured by natural selection and conveys a net advantage on an animal species

Question 34

Four main responses for anti- predatory behaviour.

Answer 34

Decrease detection by predators
Prevent an attacks /captured during an encounter with a predator
Behaviour once captured
Group living

Question 35

Decrease detection- camouflage

Answer 35

Pinnipeds vary in adult colour and pattern, ranging from uniform, white to black or brown and from a solid coloration to subtle spotted or bold markings
Neonatals often have radically different colour and pattern from those of adults
Sexually dichromatic pinnipeds a highly polygons and copulate on land , suggesting a role for male coloration in contest for access to females

On land species in which adult or pops have white pelage live in Arctic regions, neonates are black for species lacking terrestrial predators on island or in caves
At sea, spotted species forage in a well lit shadow, water is on the shelf , dark pinnipeds forage in waters off shelf

Question 36

What is concealment?

Answer 36

Staying in dense vegetation

Question 37

Prevent capture- protean behaviour

Answer 37

this occurs in many animals and occurs when they are about to get caught

Extremely erratic behaviour during escapes with random turns, and reversals

Question 38

What is predator inspection behaviour?

Answer 38

Form of pursuit deterrence in some cases (let the predator know it’s been seen)

May also get information on the predator

Question 39

What is behaviour once captured?

Answer 39

Fighting back
Manoeuvre out of jaws
Fear sounds upon capture
Other predators might fight over pray, given the prey a chance to escape
Play dead

Question 40

What are social defences?

Answer 40

Aggression
Warning others of the attack through either alarm calls or behavioural changes
Dilution effect

Question 41

What is the dilution effects?

Answer 41

Benefits to the individual and not the group- the group provides cover to individuals and reduces an individual chances of detection
Advantageous as long as attack rate does not increase proportionally with size group
Effective regards of presence or absence of other advantages to group live in
Selfish herds