Marine Reptiles Sea Snakes 65 species – Mainly tropical (Indian, Pacific) Coral reefs, open ocean

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 1000+ 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 15-16 years; females at 10-12 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 • 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. 11-11

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 videovideo • 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. 11-12 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. 11-17 Skua Arctic tern Skimmer

11. Herring gull Common tern Pomarine jaeger Black skimmer

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. 11-21

14. Brown pelican Fig. 11-24 • 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 videovideo • 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