Marine%20Reptiles%20and%20Birds

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Chapter 11 Marine Reptiles and Birds
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Marine Reptiles

• Reptiles adapted for success on land, then used
  the same characteristics to return to the sea and
  gain success there as well
• Modern-day reptiles include
• crocodilians
• turtles
• lizards
• snakes
• All are represented in the marine environment

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Physiological Adaptations

• Advanced circulatory system in which circulation
  through the lungs is nearly completely separate
  from circulation through the rest of the body
• Kidneys are efficient in eliminating wastes while
  conserving water, allowing reptiles to inhabit
  both dry regions and the salty ocean
• Skin covered with scales and lacking glands
  decreases water loss

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Marine Crocodiles

• Best adapted to the marine environment is the
  Asian saltwater crocodile (Crocodylus porosus)
• Largest living reptiles (males can grow up to 6
  to 7 m long)
• Feed mainly on fishes
• Drink salt water and eliminate excess salt
  through salt glands on their tongues
• Lives along the shore, where it nests

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Marine Crocodiles

• Females reach sexual maturity at 10 12 years of
  age, males mature at 16 years.
• Elevated nests contain 40 60 eggs, incubation
  period is 90 days
• Communicate with calls or barks
• Good navigational skills, can return to home
  estuary after being displaced long distances,
  using clues from sun and earths magnetic field

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Sea Turtles

• Seven species inhabit worlds oceans
• Adaptations to life at sea
• protective shells that are fused to the skeleton
  and fill in the spaces between the vertebrae and
  the ribs
• outer layer of shell composed of keratin
• inner layer composed of bone
• carapace dorsal surface of the shell
• plastron ventral surface of the shell
• leatherback turtle lacks shell and has a thick
  hide containing small bony plates

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Sea Turtles

• Adaptations to life at sea (continued)
• shell is flattened, streamlined, reduced in size
  and weight, for buoyancy/swimming
• large fatty deposits beneath the skin and light,
  spongy bones add buoyancy
• large fatty deposits beneath skin and spongy body
  also aid in buoyancy
• front limbs are modified into large flippers
• back limbs are paddle shaped and used for
  steering and digging nests

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Sea Turtles

• Behavior
• generally solitary, interact for courtship and
  mating
• remain submerged while at sea breathe air but
  can stay under water for as long as 3 hours
• alternate between feeding and resting during the
  day
• sleep on the bottom under rocks or coral, in deep
  water, sea turtles can sleep on surface

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Sea Turtles

• Feeding and nutrition
• have a beak-like structure instead of teeth
• green sea turtle is the only herbivore, others
  are carnivorous
• leatherback sea turtles eat jellyfish
• large amounts of salt consumed with food and
  water are eliminated as concentrated tears
  through salt glands above the eyes

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Sea Turtles

• Reproduction
• courtship males court females before mating
  males may compete for a female, or 1 female may
  mate with several males and lay eggs fertilized
  by several different males thereby increasing
  genetic diversity of population
• nesting females dig shallow pits on the beach,
  usually at night, and bury eggs, clutch size is
  between 80 150 eggs
• Single female can lay several clutches of eggs at
  2 to 3 week intervals
• development and hatching
• average incubation time is 60 days
• temperature determines development time and sex
  ratio
• hatchlings rush for the safety of the sea after
  hatching

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Sea Turtles

• Turtle migrations
• migrate hundreds to thousands of kilometers from
  feeding grounds to nesting beaches
• females return repeatedly to beaches where they
  were born to nest
• some breed on a 2- or 3-year cycle
• many hypotheses explaining method for sea turtle
  navigation over long distances
• utilize smell and taste as well as auditory cues
• sense angle intensity of earths magnetic field
• use sun

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Sea Turtles

• Sea turtles in danger
• beach erosion/alteration
• artificial lighting near nesting beaches
• sea turtles are killed when trapped in fishing
  nests, especially those used for shrimpers
• turtle exclusion devices can reduce turtle
  mortality by as much as 95 when used for shrimp
  nets
• turtles are hunted by humans for meat, eggs,
  leather and shells
• Dogs, cats and raccoons dig up nests and prey on
  eggs

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Marine Iguana

• The marine iguana of the Galápagos Islands off
  Ecuador is the only marine lizard
• Most are black, but some are mottled red and
  black
• dark coloration is thought to allow more
  absorption of heat energy
• raising body temperature allows them to swim and
  feed in cold Pacific waters
• few natural predators but vulnerable to feral
  predators such as rats, dogs and cats

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Marine Iguana

• Feeding and nutrition
• herbivores with a short, heavy snout for grazing
  on dense mats of seaweed
• larger animals dive at high tide to feed on deep
  water algae, smaller animals feed in the
  intertidal
• excess salt from consumed seawater is extracted
  and excreted by specialized tear and nasal glands

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Marine Iguana

• Behaviors
• good swimmers, using lateral undulations of the
  body and tail
• each male occupies a small territory on the
  rocks, usually with 1 or 2 females
• intruders or challengers are attacked when they
  enter the males territory
• fights between male iguanas rarely result in
  serious injury and population remains unaffected

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Sea Snakes

• Adaptations to life in the sea
• scales are absent or greatly reduced for
  streamlining
• tail is laterally compressed into a paddle
• nostrils are higher on the head
• valves in the nostrils prevent water from
  entering when the snake is submerged
• single lung reaches to the tail, and trachea is
  modified to act as an accessory lung by absorbing
  oxygen

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Sea Snakes

• Adaptations to life in the sea (cont.)
• can exchange gases through the skin while under
  water
• can lower metabolic rate to use less O2
• Feeding and nutrition
• eat mainly fish, fish eggs and eels
• most ambush prey and strike with venomous fangs
• can swallow prey more than twice their diameter
• eliminate excess salt by way of a salt excreting
  gland located posteriorly under the tongue

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Sea Snakes

• Reproduction
• congregate in enormous numbers to mate
• Sea snakes and humans
• sea snake venom is toxic to humans
• being timid, sea snakes rarely bite humans
  people eat them in Japan

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Seabirds

• 250 of 8,500 bird species are adapted to live
  near or in the sea
• Seabirds feed in the sea
• Some spend months away from land, but all must
  return to land to breed
• Types of seabirds
• shorebirds
• gulls and their relatives
• pelicans and their relatives
• tubenoses
• penguins

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Adaptations for Flight

• Feathers aid in flight and insulate
• High rate of metabolism to supply energy for
  active flight/nervous system
• Strong muscles, quick responses and great deal of
  coordination aid birds in flight
• Advanced respiratory system with 4-chambered
  heart provides more oxygen to active muscles
• Keen senses (especially sight and hearing) and
  relatively large brain to process sensory
  information effectively

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Adapting to Life in the Sea

• Large amounts of salt are consumed with food and
  salt water
• salt glands above the eyes produce tears to
  remove excess salt
• these tears have twice the salt concentration of
  seawater

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Shorebirds

• Waders feed on an abundance of intertidal marine
  life

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Shorebirds

• Herons (Family Ardeidae)
• include egrets and bitterns
• widespread, represented on every continent
• skinny legs and long necks aid in hunting
• most stand still and wait for prey to come in
  range to feed
• some stalk prey or stir up the bottom to frighten
  prey into motion so it can be caught

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Gulls and Their Relatives

• Family Laridae
• Gulls have webbed feet and oil glands to
  waterproof their feathers
• They are not true ocean-going birds, and do not
  stray far from land
• Have enormous appetites but are not selective
  feeders
• Relatives of gulls include terns

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Gulls and Their Relatives

• Gulls
• herring gulls are the most widespread, and are
  vocal, gray and white, and travel in large groups
• feeding
• noisy, aggressive, efficient predators and
  scavengers
• may drop prey with hard shells on rocks or
  parking lots to break the shell open
• highly successful at finding food and surviving,
  in some areas have reached nuisance proportions

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Gulls and Their Relatives

• Gulls (continued)
• nesting
• gather in large colonies
• not picky about nesting sites or materials
• both sexes assist in incubating 2-3 eggs
• chicks hatch in 3-4 weeks, and remain in the nest
  until almost fully grown, camouflaged by speckled
  down
• female can lay another clutch of eggs immediately
  if first one is lost
• chicks are vulnerable to predation by other
  animals and by other gulls, not uncommon for only
  1 out of every 5 hatchlings to survive

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Gulls and Their Relatives

• Terns
• small, graceful birds with brightly-colored and
  delicately-sculpted bills, forked tails
• hunt by plunging into the water for fish and
  invertebrates will steal food
• usually gregarious nesters

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Gulls and Their Relatives

• Alcids (Family Alcidae)
• Includes puffins
• look like penguins but are related to gulls
• major difference is that alcids can fly

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Gulls and Their Relatives

• Alcids (continued)
• parental care of the young
• young plunge into the water to be joined by the
  parents, and swim out to sea
• parents spend most of their time gathering food
  for hungry chicks
• adult puffins abruptly leave chicks to learn to
  swim and survive by themselves after 6 weeks of
  constant care

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Pelicans and Their Relatives

• Pelicans (Order Pelecaniformes) include gannets,
  boobies, cormorants, darters, frigatebirds,
  tropicbirds
• Have webs between all 4 toes
• Upper mandible is hooked in pelicans, cormorants
  and frigatebirds
• Many are brightly colored, or have head adornments

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Pelicans and Their Relatives

• Pelicans (Family Pelecanidae)
• large birds preferring warm latitudes and
  estuary, coastal and inland waters
• require a large fish population to support
  colonies of large birds
• feed just under the waters surface using pouches
  as nets
• a sac of skin that hangs between the flexible
  bones of the birds lower mandible

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Pelicans and Their Relatives

• Boobies
• dive into the sea from 18-30 m up to fish
• species lay differing numbers of eggs this is
  thought to reflect the reliability of the food
  supply around where they nest
• Cormorants
• swim along the surface scanning for fish, then
  plunge deep to pursue them
• lacking oil glands, they must periodically dry
  their wings in order to fly

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Pelicans and Their Relatives

• Cormorants (continued)
• most are strong fliers, but the Galápagos Island
  species is flightless
• guano cormorant of the coast of Peru valued for
  its guano (bird manure)
• Frigatebirds (Family Frigatidae)
• lightweight body and near 2 m wingspan
• lacking oil glands and cannot waterproof their
  feathers if forced to settle on ocean surface
  most likely will drown
• hence they feed by skimming surface with their
  bills
• pursue/attack other birds to steal prey

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Tubenoses

• Albatrosses (Family Diomedeidae)
• gliders with wings nearly 3.5 m long
• most live in the Southern Hemisphere where winds
  circle the earth without encountering land
• usually come to land only to breed
• elaborate courtship displays precede mating
• 1 egg is incubated by both parents on a
  volcano-shaped nest, and the young are fed on
  stomach oil, then regurgitated fish

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Penguins

• Penguins (Family Sphenisciformes)
• Bird most adapted to marine lifestyle
• Awkward on land, but swift swimmers
• flap their wings to swim
• torpedo-shaped bodies are streamlined
• flat, webbed feet are used for steering
• leap from the water to breathe
• Eat fishes, squid and krill
• Eaten by leopard seals and killer whales

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Penguins

• Adelie penguins lay eggs in summer emperor
  penguins in mid-winter
• Female emperor penguin lays 1 egg, which the male
  incubates for 2 months while she visits her
  feeding grounds
• egg sits on his feet, covered by a fold of skin
• male can feed the chick a secretion from his crop
  if it hatches before females return
• cropa digestive organ that stores food before it
  is processed

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Penguins

• female returns with food in her crop for the
  chick, and male can feed
• both parents help to feed the chick once it
  reaches 6 weeks
• by summer, the chick can feed itself, and is
  ready to enter the sea