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Marine Reptiles Sea Snakes

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Presentation on theme: "Marine Reptiles Sea Snakes"— Presentation transcript:

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

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