1. Marine Reptiles and Birds
Chapter 11
Marine Reptiles and Birds

2. Marine Reptiles
Ancestors of modern reptiles appeared about 100 million years ago.
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

3. Amniotic Egg
An amniotic egg is covered by a protective shell and contains:
amnion: a liquid-filled sac in which the embryo develops
yolk sac: sac where yolk (food) is stored
allantois: an additional sac for disposal of waste
chorion: membrane lining inside of the shell providing a surface for gas exchange during development
Evolution of amniotic egg allowed longer development (within egg) eliminating predator prone larval stage and because eggs are laid in dry places, aquatic predators are avoided
Copulatory organs allow efficient internal fertilization

4. Figure 11-1 AMNIOTIC EGG.

5. Physiological Adaptations
Other adaptations helping reptiles survive on land and in the ocean include:
Advanced circulatory system in which circulation through the lungs is nearly completely separate from circulation through the rest of the body
more efficient method of supplying oxygen to animal’s tissues
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

6. 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

7. 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 earth’s magnetic field

8. Figure 11-3 (a) SEA TURTLE SPECIES.

9. Figure 11-3 (b) SEA TURTLE SPECIES.

10. Figure 11-3 (c) SEA TURTLE SPECIES.

11. Figure 11-3 (d) SEA TURTLE SPECIES.

12. Figure 11-3 (e) SEA TURTLE SPECIES.

13. Figure 11-3 (f) SEA TURTLE SPECIES.

14. Figure 11-3 (g) SEA TURTLE SPECIES.

15. Sea Turtles Seven species inhabit world’s 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

16. Figure 11-4 (a) SEA TURTLE ANATOMY.

17. 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

18. 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

19. 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
pharynx is lined with sharp spines to hold slippery prey
digestive system adapted to withstand stings
large amounts of salt consumed with food and water are eliminated as concentrated tears through salt glands above the eyes

20. Table 11-1 FOOD PREFERENCES OF MARINE TURTLES.

21. Figure 11-6 (b) SEA TURTLE NEST.

22. 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
green sea turtles feed on grasses in warm, shallow continental waters, but breed on remote islands thousands of kilometers away
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 earth’s magnetic field
use sun

23. 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

24. Figure 11-A TURTLE EXCLUSION DEVICE.

25. 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

26. 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

27. 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 male’s territory
fights between male iguanas rarely result in serious injury and population remains unaffected

28. Sea Snakes
Descendants of lizards that have lost their limbs as an adaptation to a burrowing lifestyle
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

29. 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

30. Sea Snakes Reproduction Sea snakes and humans
3 oviparous species lay eggs on land
others are viviparous, with females retaining the eggs within their bodies until they hatch
congregate in enormous numbers to mate
male sea snakes have two penises called hemipenes
gestation period ranges from 4 to 11 months, young can swim at birth
Sea snakes and humans
sea snake venom is toxic to humans
being timid, sea snakes rarely bite humans; people eat them in Japan

31. Sea Snakes Sea Snakes and Humans toxin can be highly toxic to humans
sea snakes timid by nature, rarely bite humans, no accounts of attacking swimmers
in Japan, sea snake consumption supports a major fishery

32. 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

33. Adaptations for Flight
Homeothermic—maintaining a constant body temperature
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

34. 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

35. Figure SALT GLANDS.

36. Shorebirds Waders that feed on an abundance of intertidal marine life
Include oyster catchers, plovers and turnstones, sandpipers and curlews, avocets and stilts and herons
Oystercatchers (Family Haematopodidae)
oystercatchers use long, blunt, vertically-flattened orange bills to slice through adductor muscles of bivalve molluscs
use bills to pry limpets off rocks, crush crabs and probe mud

37. Shorebirds Plovers and Turnstones (Family Charadriidae) Plovers
have short, plump bodies with bills resembling a pigeon’s, and are shorter than other waders
have nests characteristic of waders, built in depressions or hollows on the ground
Turnstones
heavyset birds, use slightly upturned bills as crowbars to turn over stones, sticks and beach debris in search of food

38. Shorebirds Sandpipers and Curlews (Family Scolopacidae) Sandpipers
are relatives of plovers and oystercatchers
feed on small crustaceans and molluscs in sand as tide recedes
Curlews
long-billed curlew uses bill like a forceps to extract shellfish from their burrows

39. Shorebirds Avocets and Stilts (Family Recurvirostridae)
avocets and stilts have very long legs, elongated necks, and slender bodies
avocets wade through shallow water, moving a partially opened beak from side to side through the water, to feed
stilts probe the mud for small animals (e.g. insects, crustaceans) with their bills

40. 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

41. 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, skuas, jaeger birds, skimmers and alcids

42. Gulls and Their Relatives
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

43. Gulls and Their Relatives
Gulls (continued)
nesting
highly gregarious; 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

44. 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
Skuas and Jaegers
very aggressive omnivores and predators
“hawks” or “vultures” of the sea
jaegers will pursue other birds to steal their prey

45. Gulls and Their Relatives
Skimmers (scissorbills)
small birds with pupils that are vertical slits and a flexible lower jaw protruding much farther than the upper bill
fly over water and use the lower bill to create ripples at the water’s surface that attract fish
fish are then collected by flying along the same path over the water a second time

46. Gulls and Their Relatives
Alcids (Family Alcidae)
Include auks, puffins and murres
look like penguins but are related to gulls
convergent evolution: similar selective pressures brought about similar adaptations in unrelated groups of animals
ecological equivalents: different groups of animal that have evolved independently along the same lines in similar habitats, and therefore display similar adaptations
major difference is that alcids can fly

47. Figure 11-20 CONVERGENT EVOLUTION.

48. Figure GIANT AUK.

49. Gulls and Their Relatives
Alcids (continued)
nesting and reproduction
alcids gather in dense, noisy colonies in the cliffs along the northern Atlantic and Pacific oceans in early spring
both parents care for 1 pear-shaped egg
parental care of the young
young murres plunge into the water to be joined by the parents, and swim out to sea
alcid 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

50. 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

51. 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 water’s surface using gular (throat) pouches as nets
gular pouch: a sac of skin that hangs between the flexible bones of the bird’s lower mandible

52. Pelicans and Their Relatives
Boobies
dive into the sea from 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

53. 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

54. Figure FRIGATEBIRD.

55. Tubenoses
Tubenoses (Order Procellariiformes) include petrels, albatrosses and shearwaters
Have obvious tubular nostrils on their beaks which join with large nasal cavities within the head
Nasal glands secrete concentrated salt solution
Stomachs contain a large gland that produces a yellow oil composed of liquefied fat and vitamin A, used for feeding hatchlings and defense

56. 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

57. Tubenoses Petrels (Family Hydrobatidae)
storm petrels are small birds with long legs with a characteristic, fluttering flight
feed with legs extended and feet paddling rapidly just below the surface
form long-term pair bonds for breeding
diving petrels resemble auks
live only in the Southern Hemisphere in year-round cold water
spot prey from the air, perform a headlong dive, and pursue prey by “flying” underwater

58. 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

59. 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 female’s return
crop—a digestive organ that stores food before it is processed

60. 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