Transcript Marine Reptiles, Birds, & Mammals

Marine Reptiles
 The first vertebrates originated
in the ocean
 About 350 million years ago,
vertebrates came onto land
Descended from bony fishes
Bony Fish
(350 MYA)
Amphibians
(285 MYA)
Reptiles
(200 MYA)
Birds
Mammals
Harsher conditions ashore:
-no more water for support
-developed new ways to move
All land vertebrates evolved two
pairs of limbs
Called tetrapods: “fourfooted”(even snakes)
Evolved lungs & ways to stay moist
General Characteristics of Class Reptilia
• Dry scaly skin to protect against water loss
• Lay eggs
– Sex is determined by the temperature of
the environment at a time during
develop.
• Ectothermic
– Body temperature is regulated by
environment and behavior
– Basking in sunlight to warm and
swimming to cool off
• Limited to tropical and subtropical habitats
Adaptations of Reptiles to Land
• Lungs for breathing so cannot obtain
oxygen from water
• Amniotic egg-large yolk to nourish its
young and a leathery shell to prevent
dessication
• Internal fertilization and eggs laid on land
• 3 or 4 chambered hearts (more efficient at
circulating oxygenated blood)
Adaptations of Reptiles to Land
• Salt glands- remove salt from their blood
– Found above eyes
– Salt excretions help conserve water and
wash sand form their eyes
• Concentrated urine to conserve water
Order Crocodilia
• Most advanced of all reptiles
• Female lays eggs in a nest and provides
limited care for its young for several wks
• Eyes and nostrils are positioned to be
above water while croc is submerged
• Well developed senses (but cannot see
underwater)
• Opportunistic predators (carnivorous)
– Food is mostly stored as fat and they
can go years without a meal
Order Squamata- snakes
• All species of sea snake are venomous
• 1 to 2 meters in length
• Flattened body side to side and paddle tail
aid in swimming
• Some have live birth others must lay eggs
on land
• Lungs are highly inflatable and they can
dive for 2 hours
Order Squamata- Iguana
• Amblyrhynchus subcristatus
• Live on the Galapagos Islands southwest
of South America
• Dive in cold water to find algae to eat
– Warm up by basking in sun
– Remove salt w/ salt glands
• Under threat by human introduced animals
like cats, dogs and rats and human
pollution
Order Chelonia
• Sea turtles are the most widely distributed
reptile
• All species are endangered
Order Chelonia
Sea Turtles
Biology
• Found year round in the tropics but higher
latitude in the summer
• Most feed in shallow water
• Long migrations between feeding and
breeding grounds
• Males spend entire life at sea, females
return to land to lay eggs
• Nest every other year and a couple of
times a season
Life Cycle
• 50-170 eggs , 6-13 weeks to hatch
• Emergence is typically at dusk and
hatchlings head towards the brightest
horizon
• Lost years- lead largely pelagic existence
• Females return to natal breeding ground
• Live more than 50 yrs, repro. between 10
and 30 yr old
Sea Turtle Body Plan
• Differ in size, pattern of scales on the shell
• Sea turtles can survive up to 200 yrs
• Body plan is well adapted to marine
environment
– Fatty deposits for buoyancy
– Light bones for buoyancy
– Streamlined shells and flippers
• Dive up to 40 minutes
Leatherback
Dermochelys coriacea
• 6 ft long
• Feed on jellyfish
Green
Chelonia midas
• 3.3 ft
• Juveniles eat
molluscs,
crustaceans and
jellyfish
• Adults eat seagrass
and algae
Loggerhead
Caretta caretta
• 3 ft long
• Eat benthic
crustaceans
and molluscs
Hawksbill
Eretmochelys imbricata
• 2-3 ft long
• Eat sponges and benthic invertebrates
Kemp’s Ridley
Lepidochelys kempii
• 2-2.6 ft long
• Eat crabs, shrimp and molluscs
Sea Turtle Nesting Behavior
• Use their flippers to dig a hole once they
select a nesting site
• Eggs are laid into the hole and covered
with sand
• 2 months later the eggs hatch
• Between hatching and 20 years of age are
the lost years
Hatching Success
• Nests with temps below 28.7 produce
mostly males
• At risk for predation
• Risk of suffocation
• Risk of drowning
• 80% Hatch success rate
• Only 1 or 2 turtles survive to maturity
Human Interactions
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Developing and building on the shoreline
Commercial fishing
Erosion of shoreline
Disturbing nesting beaches
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Common
Name
Turtles
Anatomy
Crocodile
Rarely larger than 20 ft long.
Largest reptile
Snakes
Flattened, legless, a paddle
like tail for swimming
Iguana
4 legs, flattened tail for
swimming
•Armor like shell fused to
backbone
•Legs modified as flippers
Common Name Feeding
Turtles
Algae and small
invertebrates like jellyfish
Crocodile
Vicious predators
Snakes
carnivorous
Iguana
seaweeds
Common Name
Examples
Turtles
7 species: Green, hawksbill,
leatherback, kemps, etc.
Crocodile
1 species?
Snakes
55 known species
Iguana
Galapagos island iguanas
Common Name
Life History
Turtles
Born on land, life in open
water, return to land only to
lay eggs
Stay on the coast but may
migrate to open ocean
Crocodile
Snakes
Totally marine existence
Iguana
Live on land, feed on food
from the ocean