Australian Marine Mammals! Flashcards
(43 cards)
What are the 3 groups of Marine mammals found in Australia?
*Order carnivora- Pinnipeds (include seals, sea lions)
*order cetacea - Cetaceans (whales, dolphins)
* order sirenia - Dugongs
How many species does australia have?
60-130 species
Marine Mammal list
Air breathers
endothermic
feed young milk
possession of hair - seal and seal ions
What is the conservation status of marine mammals?
- > 25 - 37 % of marine mammals are Threatened: i.e.,
Critically Endangered, Endangered, Vulnerable
* Another almost 40 % may also be at risk but are Data Deficient (means little known about them- cant determine robustly their risk)
- > 75 % of all marine mammals currently experience high levels of human impact …
What are direct and indirect threats to marine mammals?
Direct threats causes mortality
– directed harvest (historical whaling)
– entanglement in fishing gear
– noise pollution from military and seismic sonar - suffer decompression sicknes
– boat strikes
indirect threats causes morbidity/ decline in reproductive rate
– water pollution
– habitat loss from coastal development
– loss of prey or other food sources due to poor fisheries management
– climate change
What are the most endangered marine animals?
North Atlantic right whale - small populations remaining
Smallest of Cetaceans -vaquita
Blue whales - largest animal on earth.
Where do marine mammals come from?
- Diverse assemblage- several origins
- Evolved from terrestrial mammals
- Secondarily aquatic
- Returned to the sea ~50 mya- differentially adapted
- Adapted to a marine existence - some moved into freshwater systems
whales and dolphins - hippopotamus
seals - bears
dugongs - elephants
How have marine animals adapted throughout evolution?
locomotion
thermoregulation
diving
How do they collectively show characteristics of locomotion?
- streamlining of body
- buoyancy: integument & blubber
- propulsive force - water is dense and require strength so;
- seals: 4 limbs that assist in movement
- cetaceans & sirenians: axial body & tail
- steering: fore flippers = hydrofoils
How does thermoregulation function in marine mammals?
- Warm blooded animals and because water is a good conductor they lose heat to water
It requires insulation, counter-current systems - vascular system redirects heat to the core of the body, large body - surface area to volume ratio is small
How do marine mammals dive?
- Air breathing raise to the surface to get air
- Efficient respiratory exchange - able to remove excess of carbon dioxide and breathe in fresh air.
- Exchange > 80% air with each breath
Increased oxygen store during dive (in blood, muscle)
- High blood volume compared to terrestrial animals
- they will have Extra vessels, sinuses
- High haematocrit (rbc)
- High Hb
- High Mb (myoglobin) in muscle
So… blood & muscle holds a lot of O2
By increasing oxygen store, divers ca increase dive depth
& duration
What marine animal is considered the champion diver?
Southern elephant seal
1700m
Cuvier’s beaked whale
depth of 2992 for 2hrs
aerobic dives
What are some examples of pinnipeds?
Seals and sealions
In regards to the pinnipeds, what temperatures do they located in?
Polar to temperate coastal Australian - tied to land or ice to breed
What are types of pinniped species? and why are they semi-aquatic?
Eared seals: Otariidae = fur seals and sea lions
3 series in SA
True Seals: Phocidae = cold water seals
several in Southern ocean and in antarctica
What are distinct characteristics of Oteriidae?
front flippers create thrust for swimming and when on land mostly use hind flippers
ear pinne
fur - insulate with combination o f blabber
mobile manuavable - walk and run on land
rotate pelvis under the body and use their hind limbs
1. Australian fur seal
2. Australian sea lion
3. Long nosed fur seal
4. Antarctic fur seals
Which of the pinnipeads in Australia are considered endangered?
Australian sea lion
found in south aus and western aus, islands and mainland
14700 approx.
Endangered and in need of special protection
why are Australian sea lions endangered?
- Hunted
- Abnormal asynchronous breeding cycle
– 5 - 7 month breeding cycle
– 17-18 month non-breeding
(cf other seals have 12 month cycle)
- Fragmented small populations (past harvest)
– populations have not recovered from exploitation - Small size of breeding colonies
- High site fidelity of females
- Low reproductive rate
– few breeding, long dependency phase, energetically expensive for females - High mortality
– pup, pup at weaning (disease, nutritional stress, attacks by males)
– adults (fisheries bycatch) - Exposure to human activities
– gill nets, lobster pots, entanglement in lines, poaching, pollution, disease…
What are considered True seals?
Phocids
Their body shape is different, they cannot rotate pelvis, lumber on land (bouncing on abdomen)
dive deeply
in water very mobile - rear flippers create thrust for swimming.
- weddell seal - live beneath and above ice and making breathing holes with teeth, they have vocalisation
- leopard seal-
- crabeater seal - most abundant, eat krill, find krill/bait balls, close the mouth and use teeth as a type of filter
- Elephant seal - polar and subpolar, territorial, with beach master
What animal is found the cetacea group?
Whales
found in polar to tropical regions (found all over the world)
ancestors shared with hippopotamuses
others are migratory
dolphins, whales and porpoises
What suborders are in the order cetacea?
and what are two types of species?
- Toothed - odontoceti
- Baleen - mysticeti they have hair like teeth cornified matrix - take large amounts of water taken in, they lift their tongue pushing water out through the baleen filter.
What are diagnostic features of whales?
Live
1. Location
2. Body, fin size & shape
3. Blow shape and size
4. Diving & surfacing behaviour
5. Social grouping
6. Reaction to vessel
Carcass
1. & 2. above +
3. Head / skull characters
4. No. and size teeth, or
Size, colour, no. baleen plates
5. Colour pattern
6. Number stranded
What characteristics do Odontocetes have?
toothed whales
“small” body size
single blowhole
asymmetrical skull
Echolocation for prey capture - work out the direction
highly social - live in pods or schools
What is the largest Odontocetes?
Sperm whales
squid feeders
