Transcript Marine Reptiles, Birds, and Mammals We are near the end… evolutionarily that is.

Marine Reptiles,
Birds, and Mammals
We are near the end…
evolutionarily that is.
Introduction
• Finally, we’re into the friendly, furry, and sometimes
intelligent stuff.
• This chapter is why most folks think about becoming
marine biologists in the first place.
• We’ve moved onto land (in some cases back to water).
• Wings, flippers, legs and feet have replaced fins in
some cases.
Introduction
• What is the first challenge of living on land??
• How do you stay hydrated??
• Second challenge…how do you move?
• Animals that solved this problem are called “tetrapods,” literally
four-footed.
• Solving these issues in other ways meant literally returning to
the sea. We’ll examine animals that fit into both groups.
Marine Reptiles
~7,000 spp.
Snakes, lizards,
turtles, crocodiles
• Ectothermic
• Lungs
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Salt glands
Excrete uric acid with kidneys
Scales
Oviparous (egg laying)
Must return to land to lay eggs
Marine Iguana
• Galapagos Islands
• Dive for up to 30 min.
• Eat kelp and other algae
• 60-140 cm long
• Max weight 12 kg
• Salt glands in the nose
• Lay 2-3 eggs
Marine iguana, Amblyrhynchus cristatus
Saltwater Crocodile (Crocodylus porosus)
• Indopacific location
• Length 7 m (26.5 ft)
• Largest living reptile
•Lays 40-50 eggs
• Considered dangerous
• Salt glands in the eyes
• Lives estuarine waters
(generally low salinity)
Some marine reptiles are threatened or endangered such as this
green sea turtle, Chelonia mydas
Many sea turtles like this hawksbill and
leatherback are also under protective status.
Eretmochelys imbricata
•Mottled shell
•Hawk-like bill
•Shell length 30-36 in.
•Weight 100-200 lbs.
•Tropical Reef turtle
•Status: Endangered
•Eat mostly sponges
Dermochelys coriacea
•Largest sea turtle
•Black and white coloration
•Shell length 6 ft.
•Weight 1400 lbs.
•Pelagic
•Status: Endangered
Eat mostly jellyfish
Kemp’s Ridley Turtle, Lepidochelys kempi
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Smallest sea turtle
Shell length < 30 in.
Weight 80-100 lbs.
Nest in Tamaulipas, Mexico
Status: Endangered
Eat mostly crabs
-All sea turtles return to land to lay eggs. Many swimming to the
same beach they hatched from to complete their life cycle.
-Use of TED’s has greatly increased turtle survival when
encountering fishing nets.
Turtle excluder device (TED)
Green sea turtle laying eggs.
Sea snakes (55 spp.) are mostly marine, but a few do
return to land to lay eggs.
Sea Snake, South Pacific
• Neurotoxic venom causes death in minutes
• Relatives of the cobra
• Eat fish
• Salt gland in the mouth
Marine Birds
Seabirds, Penguins, Tubenoses,
Pelicans, Gulls,
Shorebirds
Shy albatross
Marine Sea Birds: General Stuff
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Homeothermic ectotherms (first time we’ve seen this!)-essentially
maintaining a constant internal environment.
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Use feathers and oil gland to insulate (preening)
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Fat layers insulate as well
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Countercurrent exchange (CCE) in their feet to reduce heat loss
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Excellent color vision! Have natural UV filter (enhances greens and blues)
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Oviparous (egg laying)
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Salt glands for osmoregulation
Feathers
• Modified bone
• Gave rise to hair
• Insulation
• Facilitates flight
How CCE works.
• Blood vessels are
maintained very
close together so body
heat warms outgoing
blood, while returning
blood picks up heat
before entering body.
Conserves body heat.
Seabirds (more…)
• Carnivores or scavengers?
• Uric acid excretion
• Intense migrations
•Commercial value?
-Eco-tourism
-Guano used for fertilizer!
Brown booby, Sula leucogaster
Transpolar Migration of the Arctic Tern!
• They literally go all
the way around….
Others just travel one continent to the other…
Gannet, Morus bassanus
This Gannet starts in Quebec, but ends up on the East Coast of the US.
Marine Bird Feeding Strategies
•Deep-water waders
•Shallow-water waders
•Pirates
Bill shape
adaptations:
a. Plungers
b. Divers
c. Dippers
d. Skimmers
Others: Marine/Esturarian Feeding Strategies
Deep Water Wader: Blue Heron, Snowy Egret
Shallow Water Wader: Willet, Sandpiper, Plover
Pirates: Laughing gulls, Herring gulls
Diving Birds: Commorants, Penguins, Puffins
Penguins: The odd bird out…
•Modified feathers have become fins.
•Eat mostly fish, squid, and krill.
•Prey for others (leopard seals, sharks,
Orcas.
•Tough nesting routine!
•Eggs of “Emperors” can freeze in 20 sec.
on ice pack, if not transferred from female
to male in time.
Emperor penguin Aptenodytes foresteri
Seals, Seal Lions, Walruses
Seals, Seal Lions, Walruses
• Also known as pinnipeds for their paddle shaped flippers.
• Most pinnipeds are predatory making a living on squid and fish.
• Many have been hunted for blubber (fat).
• Due to the cold waters they inhabit, pinnipeds have evolved
fairly large bodies (gigantism).
Marine Mammals
• 4600 spp. of mammals, including humans.
• Most are viviparous (live young) and placental
(young receives nurishment from placenta).
• Newborn is fed by
mammary glands.
• Five groups of marine
mammals are found.
Sea lion or Seal?
-Nearly hunted to extinction, some seals (19 spp.) are now recovering nicely.
-This elephant seal is known for its huge proboscus!
Northern Elephant Seal, Mitounga angustirostris
-As a species, they were nearly hunted to extinction (~100) in the late 1800’s.
-Although saved and miraculously rebounding (~100k) today, the genetic
diversity is very skewed (much inbreeding).
-Still others such as this harp seal (and pup), considered valuable
in the fur trade have been aggressively managed (300K taken per
year).
Harp seal (Phoca groenlandica)
-Many marine mammals now enjoy protection under an Act of
Congress by the same name (Marine Mammal Protection Act, 1972).
Walrus, Odobenus rosmarus
a particularly large,
clam-eating
pinniped.
Contrary to popular belief, the tusks aren’t used for eating, but
moving from water to ice pack and for defense.
Sea Otters
• At 25 kg, the sea otter is the
ultimate salt water glutton for it’s
size, eating 25 -30% of it’s body
weight per day!!
• Although hunted to near
extinction, their populations are
recovering.
• They provide a great ecosystem
benefit in keeping the population
of sea urchins from growing out
of control...and thus saving kelp
forests!
Sea Otter, Enhydra lutris
Polar Bear (Urus maritimus)
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Cute, soft, furry, and they can kill and eat you!!
Polar bears are protected. Habitat loss a major issue.
Females birth 2-3 cubs commonly.
Mostly carnivores, but there are always exceptions.
Many polar bears are “lefties.” (Who figured that one out?!)
Manatees (Trichechus manatus) & Dugongs
(Dugong dugon)
• Mantees and Dugongs are
slow moving herbivores.
• Some reach 15 ft in length
and weigh up to 1350 lbs.
• Many live in Florida and
spend their days munching
on sea grass, a favorite
food.
Cetaceans (Whales, Dolphins and Porpoises)
• An excellent example of convergent evolution
(different spp. developing similar traits due to similar
lifestyles.)
Dolphins with legs?? Nope. The second set of
“legs” disappears upon final development.
Dolphins and Porpoises
Spinner Dolphin, Stenella longirostris
Which is which??
Dolphin:
Length: adult coastal 2.2-3.0 m; adult pelagic 3.3-3.8 m
Dorsal Fin: moderately high and falcate
Teeth: conical
Head: distinct thick beak
Color: body gray to black dorsally becoming lighter ventrally
Porpoise:
Length: adult 1.4-1.7m
Dorsal Fin: broad-based, low and triangular
Teeth: spade-shaped
Head: blunt-nosed
Color: body dark gray or black dorsally, light gray mid-ventrally, white ventrally
Whaling is still legal…
Identifying cetaceans
Food acquisition!!
Intelligence??
Social Behavior
Breaching!
Stranding
Huge Migrations are needed for food.
Sex is sometimes challenging.
Or not?
Births in captivity are becoming more common.
As we understand more about cetaceans, we may
yet breach the communication barrier.