- 2nd largest fish - max length ~1200cm - max age ~50 yrs - gestation 1–3.5 years -> litter size 1–6 pups - length at birth ~150–200cm - passive filter-feeders -> feeds on zooplankton (copepods, crustacean larvae, fish eggs) - aggregates seasonally in temperate continental shelf waters where there is ↑ zooplankton (oceanic & thermal fronts, headlands, islands & enclosed bays with strong tidal flow) - known to have long seasonal migrations -> inc transoceanic & transequatorial (crossing equator) movements

- long-lived - reptiles - natal philopatry -> return to area the animal was born in - site fidelity -> tendency to return to prev visited locations - migratory, navigate - temp-dependent sex determination

- Dermochelys coriacea - globally vulnerable 2013 - native UK fauna (animals of UK) - eats jellyfish (& plastic) - esophageal papillae - pelagic throughout life - can thermoregulate by ↓ blood flow to extremities in cold (large size helps) - deepest diver 1000m

Eretmochelys imbricata - globally: Critically Endangered (2008) - hawk-like beak - feeds on sponges on coral reefs – vulnerable to climate change - nests across tropics but not in large numbers - taken for tortoiseshell

Lepidochelys kempii - IUCN: Critically Endangered (2019) - eats crabs - arribada nesting -> mass nesting event -> come ashore to nest & lay eggs on beach - only nested in Gulf of Mexico -> huge project to relocate to new areas -> now nesting in Texas & Florida

Lepidochelys olivacea - IUCN: Vulnerable (2008) - eats fish and salps (type of zooplankton) - arribada nesting - eggs harvested legally at Ostional, Costa Rica

Caretta caretta - IUCN Vulnerable (2015) - eats crustacea and fish - large head/jaw - infaunal mining (foraging strategy) - bycatch -> BIG issue

Natator Depressus - IUCN: Data deficient - eats jellyfish & invertebrates - smaller clutch size (no. eggs in nest)

Chelonia mydas - IUCN: Endangered (2004) - feeds on seagrass & algae - edible turtle -> most commonly eaten

- mating occurs in water - sperm stored - oviparous -> lay eggs - eggs are soft shelled -> water & gasses can move across membrane & are source of Ca - eggs retained internally & all laid together as clutch - no parental care - produce 1000s of offspring

hatchlings orientate to light, slope & perpendicular to waves - use Earth's magnetic field - imprint on location / sand / magnetic fields - been shown to orientate in “offshore direction” suggest innate magnetic cues once offshore

- most numerous marine mammal group (28% of marine mammal diversity) - ~50 million worldwide - 90% phocids (true seals) - found in all major oceans (& some freshwater) - all have amphibious lifestyle -> spend part of life in water, part on land

pinnipeds, turtles & basking sharks Flashcards by Evie Thompson

basking sharks info

2nd largest fish
max length ~1200cm
max age ~50 yrs
gestation 1–3.5 years -> litter size 1–6 pups
length at birth ~150–200cm
passive filter-feeders
-> feeds on zooplankton (copepods, crustacean larvae, fish eggs)
aggregates seasonally in temperate continental shelf waters where there is ↑ zooplankton (oceanic & thermal fronts, headlands, islands & enclosed bays with strong tidal flow)
known to have long seasonal migrations -> inc transoceanic & transequatorial (crossing equator) movements

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basking sharks historical threat

Basking sharks historically targeted by fisheries…

for oily rich livers
->eg. Irish fishery ~took 12,360 sharks from 1947 and 1975

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basking sharks modern threats

basking sharks also still caught as bycatch in nets & trawls
-> low reporting rates
can also easily become entangled in fishing nets & ropes
v sensitive to disturbance and harassment by ppl - propeller & boat strikes remain a danger

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marine turtles info

long-lived
reptiles
natal philopatry -> return to area the animal was born in
site fidelity -> tendency to return to prev visited locations
migratory, navigate
temp-dependent sex determination

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leatherback turtle

Dermochelys coriacea
globally vulnerable 2013
native UK fauna (animals of UK)
eats jellyfish (& plastic)
esophageal papillae
pelagic throughout life
can thermoregulate by ↓ blood flow to extremities in cold (large size helps)
deepest diver 1000m

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hawsbill turtle

Eretmochelys imbricata

globally: Critically Endangered (2008)
hawk-like beak
feeds on sponges on coral reefs – vulnerable to climate change
nests across tropics but not in large numbers
taken for tortoiseshell

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kemp’s ridley turtle

Lepidochelys kempii

IUCN: Critically Endangered (2019)
eats crabs
arribada nesting -> mass nesting event
-> come ashore to nest & lay eggs on beach
only nested in Gulf of Mexico
-> huge project to relocate to new areas
-> now nesting in Texas & Florida

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olive ridley turtle

Lepidochelys olivacea

IUCN: Vulnerable (2008)
eats fish and salps (type of zooplankton)
arribada nesting
eggs harvested legally at Ostional, Costa Rica

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loggerhead turtle

Caretta caretta

IUCN Vulnerable (2015)
eats crustacea and fish
large head/jaw
infaunal mining (foraging strategy)
bycatch -> BIG issue

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flatback turtle

Natator Depressus

IUCN: Data deficient
eats jellyfish & invertebrates
smaller clutch size (no. eggs in nest)

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green turtle

Chelonia mydas

IUCN: Endangered (2004)
feeds on seagrass & algae
edible turtle -> most commonly eaten

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turtle reproduction

mating occurs in water
sperm stored
oviparous -> lay eggs
eggs are soft shelled
-> water & gasses can move across membrane & are source of Ca
eggs retained internally & all laid together as clutch
no parental care
produce 1000s of offspring

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turtle navigation

hatchlings orientate to light, slope & perpendicular to waves

use Earth’s magnetic field
imprint on location / sand / magnetic fields
been shown to orientate in “offshore direction” suggest innate magnetic cues once offshore

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pinnipeds info

most numerous marine mammal group (28% of marine mammal diversity)
~50 million worldwide
90% phocids (true seals)
found in all major oceans (& some freshwater)
all have amphibious lifestyle -> spend part of life in water, part on land

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when did pinnipeds first appear? (in N. Pacific first)

include their ancestors

late oligocene age (27-25 Ma)
monophyletic group
-> inc organisms with common ancestor & closely related.
-> also have similar genetics
descendents from arctoid ancestors (mustelid, bear, dog)

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Phocidae

family

“true” seals

19 sp

more streamlined body
thin fur, thick blubber
largest & most widespread
no external ears
swim with hind flippers
cannot walk on all 4 limbs
larger body size (than otariids)

Odobenidae

family

walrus -> most live in Canada & Greenland

1 sp: Odobenus rosmarus

no external ear structures
elongated upper canine teeth: tusks (both sexes)
swims with hind flippers
can walk on all 4s (reflects hind limbs)

Otariidae

family

sea lions, fur seals

16 sp

walk on all 4 limbs (reflect hind limbs forward)
swim with fore flippers
external ear pinnae
more hair/fur
sexually dimorphic

Puijila

“walking seal” -> otter-like

illustrates what early steps in seal evolution looked like
~110cm long
semi-aquatic
no flippers, long tail
arctic

Enaliarctos

~29 Ma (oldest pinniped)

Oligocene->Miocene
~80kg
fish predator
flippers
(upwelling already occuring) -> so more phytoplankton -> so more fish to eat

Desmatophocidae

extinct lineage
N. Pacific
sexual dimorphic -> sexes of same sp exhibit diff morphological characteristics
less aquatic than modern pinnipeds
related to phocids

Acrophoca

early Monachinae

swan-necked seal
late Miocene->early Pliocene
hind-limb dom. swimming
1.5m length
found in Peru

Leptophoca

early Phocinae

mid-Miocene
hind-limb dom. swimming
> 1.2 m length
found in N. America & Europe

Thalassoleon

early Otariidae

late Miocene->early Pliocene (8-6 Ma)
California, Mexico and Japan
feed by biting
forelimb feeder

pinnipeds: reproductive patterns

*Odobenidae:* - 1 pup every 1 – 2 yr - weaning **2 yr** - feed during lactation *Otariidae:* - 1 pup every 1 yr (**slow** pup growth) - weaning 4 months–1yr - feed during lactation (intermittently) *Phocidae:* - 1 pup every 1 yr (**rapid** pup growth) - weaning 4–50days - **fast** during lactation

pinnipeds: life history

- need land (ice) to moult, breed (also rest) - **hauling-out** (pinnipeds temporarily leaving water) involve varying degrees of **fasting & no water** - at-sea foraging trips - delayed implantation

pinnipeds: abundance

- pops range from **few 100** individ (Mediterranean monk seal) to **8-10 mill**. individ. (harp and crabeater seal) - remarkable recovery of several pops & sp

Phocid breeding patterns

***capitol breeding:*** - build and/or store reserves... that **allow them to reproduce at later time**... **indep. of food availability** during breeding -> **single long trips** -> economical foraging strategy

Otariid breeding patterns

***income breeding:*** -> allocate **recently acquired resources** directly to reproduction - **multiple short trips** - use high energy to obtain high energy

pinnipeds: **foraging**

- feed mostly on fish & squid - social & individ. foraging ***Walrus:*** - **bottom feeder** - benthic prey -> 600+ clams per day - find prey with vibrissae (whiskers) - **stir up sediment** -> has big effect on bottom habitat ***Phocids:*** - **coastal/shallow to deep prey** (+2000m) - fish, mollusks, crustaceans - some **high-degree specialisation** (e.g crabeater & Baikal seals) - no echolocation but use whiskers ***Otariids:*** - voracious (v hungry) predators - several behavioral adaptations - **generalists** -> can live in many diff types of env & have varied diet - inhabit coastal ecosystems close to humans - feed on **commercially important sp**

describe the **grey seal** in the UK waters threats, food, reproduction

reproduction: pupping starts SW in Sept. -> ends SE in Jan. food: - **benthic & demersal prey (fish)** - sometimes seabirds - harbour porpoises - harbour seals - even **cannabalistic** threats: - fisheries **bycatch** - competition - global climate change - **zoonotic events** (eg. avian influenza)

describe the **harbour seal** in the Uk waters

pupping starts late spring - **generalists** - dives ~2-4 mins, ~40m - **mass die-offs** linked to phocine distemper virus - same threats as grey seal