1. Marine Reptiles Sea Snakes
65 species – Mainly tropical (Indian, Pacific)
Coral reefs, open ocean
Adaptations to aquatic lifestyle
Scales reduced or absent
Nostrils higher on head vs. terrestrial snakes; specialized valves that seal nostrils when submerged
Bodies flattened laterally (3-4 feet long at maturity)
Paddle-shaped tail video
Huge lung (extends into tail); gas exchange across trachea & skin
Can dive to 150 m (typically ~5 m); hold breath 2+ hours
Eliminate salt via salt gland under tongue
Ovoviviparous
Gestation 4-11 months
Few species lay eggs on shore
Venomous
Closely related to cobras
Venom typically used to kill small prey (fishes, squids)
May hunt in schools
Some actively trap prey; others lie in wait
Few natural predators (seabirds, sharks, saltwater crocodiles)

2. Marine Reptiles Saltwater Crocodile
Four-chambered heart (similar to birds)
One species – E Indian Ocean, W Pacific, Australia
Mostly inhabit mangrove forests
Largest crocodile species - Males larger than females
May reach 23+ feet and kg
Diverse diet
Fishes, crustaceans, snakes, birds, mammals, fishes
Drink seawater
Salt glands on tongues  excess salt
Slow to reach sexual maturity
Males mature at years; females at years
Eggs (usually 40-60; up to 90+) laid in mounds of mud/debris
Guarded by female
Environmental sex determination
Mostly males ~31.6 oC
Warmer or cooler: More females

5. Seabirds About 250 species Endotherms and homeotherms
Spend a significant part of life at sea
Feed on marine organisms
Webbed feet for swimming
Endotherms and homeotherms
Allows seabirds to live in a wide variety of conditions
Need considerable food to maintain body temperature in cold regions
Four-chambered heart; efficient circulatory system
Feathers (modified reptile scales) help conserve body heat
Trapped air provides insulation and buoyancy
Gland above base of tail produces oil that birds add to feathers with preening
Flight (facilitates feeding, predator avoidance, expanded range and habitat use)
Reduced body weight (hollow bones, no teeth, reduced gonads during non-breeding season, no urinary bladder)
Relatively large brain, good color vision
Salt consumption  salt glands above eyes
Nest on land
Often colonial
Frequently mate for life
Gannet

6. Fig

7. Seabirds Shorebirds (Waders) Forage/Feed in intertidal zone
Adapted for walking on shores
Most feed on infaunal invertebrates
Many with sensitive nerve endings at ends of bills to aid in prey detection
Resource partitioning via diverse bill lengths Video

8. Curlew
Willet
Sanderling
Sandpiper

9. Seabirds Shorebirds (Waders) Often ground-nesting Oystercatchers
Thick bill: open bivalves, pry limpets off rocks, crush crabs, probe for crustaceans & worms video video
Plovers and Turnstones video
Short bill; eat small animals collected near surface
Sandpipers and Curlews
Sandpipers: short bill; feed on small prey when water recedes
Curlews: long, curved bill; feed on deep-living crustaceans video
Avocets and Stilts
Long legs, bills; probe sediments for prey video
Herons (incl. egrets, bitterns)
Long bill; stand and wait predator video
Feed on small fishes, crustaceans
Oystercatcher
Fig
Plover
Sandpiper
Avocet
Egret

10. Seabirds Gulls and Relatives
Global distribution, not always near ocean
Gulls
Highly adaptable; wide distribution
Dietary generalists; creative feeding behaviors video
Nest in colonies; can produce several clutches each year
Terns
Plunge to catch near-surface prey video
Nest in colonies, often very large
Skuas and Jaegers
Aggressive predators (skuas), food thieves (jaegers) video
Ecological equivalent to raptors (skuas)
Skimmers/Scissorbills
Asymmetrical bills (lower longer) video
Skim water surface to attract prey; fly opposite direction to feed
Lesser black-backed gulls
Fig
Skua
Arctic tern
Skimmer

11. Herring gull
Common tern
Black skimmer
Pomarine jaeger

12. Seabirds Gulls and Relatives
Global distribution, not always near ocean
Alcids (auks, puffins, murres)
Countershaded; resemble penguins (convergent evolution)
“Fly” through water, pursuing prey (fishes, squids, shrimps) video
Nest on ledges and among boulders (auks, murres) or on cliffs (puffins); single pear-shaped egg guarded by both parents
Atlantic puffin
Parakeet auklet
Common murre

13. Fig

14. Seabirds Pelicans and Relatives (Pelecaniformes)
Brown pelican
Fig
Seabirds
Pelicans and Relatives (Pelecaniformes)
Webs between all four toes
Mostly coastal, tropical and warm temperate
Pelicans
Subsurface feeding with gular pouch
Dive to capture prey below surface video video
Use subcutaneous air sacs to return to surface
Boobies
Unusual courtship behavior video
Resource partitioning: foraging ranges (blue-footed – nearshore, masked – intermediate, red-footed offshore)
Dive (up to 30 m!) to capture prey below surface video
Cormorants
Swim on surface; dive (to 40+ m!) to catch prey video
Lack oil glands; must dry after swimming
Frigatebirds
Impressive courtship displays video
Skim surface for prey; may steal fish
Red-footed booby
Frigatebird
Cormorant