I. Marine Reptiles

C. 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)

I. Marine Reptiles

D. 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

II. 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

Fig. 11-11

II. Seabirds

A. 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

Curlew

Sanderling Sandpiper

Willet

II. Seabirds

A. Shorebirds (Waders)• Often ground-nesting1. Oystercatchers

• Thick bill: open bivalves, pry limpets off rocks, crush crabs, probe for crustaceans & worms video video

2. Plovers and Turnstones video• Short bill; eat small animals collected near surface

3. Sandpipers and Curlews• Sandpipers: short bill; feed on small prey when water recedes• Curlews: long, curved bill; feed on deep-living crustaceans video

4. Avocets and Stilts• Long legs, bills; probe sediments for prey video

5. Herons (incl. egrets, bitterns)• Long bill; stand and wait predator video• Feed on small fishes, crustaceans

OystercatcherFig. 11-12

Plover

Avocet

Sandpiper

Egret

II. Seabirds

B. Gulls and Relatives• Global distribution, not always near ocean1. Gulls

• Highly adaptable; wide distribution• Dietary generalists; creative feeding behaviors video• Nest in colonies; can produce several clutches each year

2. Terns• Plunge to catch near-surface prey video• Nest in colonies, often very large

3. Skuas and Jaegers• Aggressive predators (skuas), food thieves (jaegers) video• Ecological equivalent to raptors (skuas)

4. Skimmers/Scissorbills• Asymmetrical bills (lower longer) video• Skim water surface to attract prey; fly opposite direction to feed

Lesser black-backed gullsFig. 11-17

Skua

Skimmer

Arctic tern

Black skimmer

Common tern

Herring gull

Pomarine jaeger

II. Seabirds

B. Gulls and Relatives• Global distribution, not always near ocean5. 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

Common murre

Parakeet auklet

Fig. 11-21

II. Seabirds

C. Pelicans and Relatives (Pelecaniformes)• Webs between all four toes• Mostly coastal, tropical and warm temperate1. Pelicans

• Subsurface feeding with gular pouch• Dive to capture prey below surface video video

• Use subcutaneous air sacs to return to surface

2. 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

3. Cormorants• Swim on surface; dive (to 40+ m!) to catch prey video• Lack oil glands; must dry after swimming

4. Frigatebirds• Impressive courtship displays video• Skim surface for prey; may steal fish

Brown pelicanFig. 11-24

Red-footed booby

Frigatebird

Cormorant