Cetacean Adaptations II Flashcards
How often do female mysticetes usually breed?
Every 2-4 yrs
What are the 3 different types of killer whales?
Resident, transient and pelagic
What is the social structure in mysticetes?
Small groups of females and offspring- the males ‘escort’ the females
Competitive groups with several males trying to get access to one female during breeding season
What could the function of the large dorsal fins on a killer whale be?
Secondary sexual characteristic
Do Odontoceti offshore types generally live in large or small groups?
Larger group sizes
What type of group structure do bottlenose dolphins have?
A “fission-fusion” where they split up and come together for certain things e.g. they all come together for feeding
What is infanticide?
Where the mother kills her offspring within a year of birth
How many individuals can be in a group of spinner dolphins?
100-1000
How many individuals of harbour porpoise are there usually in a group?
1-3
What are the advantages of living in large groups?
Protection against predators
Easy to find mates
Cooperative feeding
What are the disadvantages of large groups?
Competition for prey
Risk of inbreeding
Risk of extirpation (group being killed) I’d subject to a large scale mortality event e.g disease outbreak
What are phocidae and what percentage of the group do they make up?
True or earless seals
90% of all seals
How many species of monk seals are there? Name them:
3
Hawaiian (Monachus schauinslandi)
Mediterranean (Monachus monachus)
Caribbean (Monachus tropicalis)
How many individuals are remaining in the Hawaiian species?
1000
What size and weight are the Hawaiian species?
2m and 150-300kg
What species of monk seal is the most critically endangered and what one is extinct?
Mediterranean= most critically endangered
Caribbean= extinct in 2008
How many individual Mediterranean monk seals are left?
350-450
What size and weight are the Mediterranean monk seals?
2.5m and 300kg
What is the reason for the decline in all the monk seal species?
Disease and human activities: hunting and fishery bycatch
What is the most abundant seal species in the world? How many are there?
Crab eater seal (Loboden carcinophagus)
7-12 million
Where are crabeater seals found?
Free floating pack ice that extends seasonally out from the Antarctic coast
What is the most likely reason for the success of the crabeater seal?
It’s specialised predation on the abundant Antarctic krill, which it has uniquely adapted a sieve like tooth structure
What is the second largest species of seal in the Antarctic after the elephant seal?
The leopard seal (Hydrurga leptonyx)
What adaptation allows the leopard seal to bite larger prey?
It has an unusually loose jaw that can open 160 degrees
