Marine Vertebrates

Marine BiologyDr. Ouida Meier

Representative Marine Phyla:

• Phylum Porifera

• Phylum Cnidaria

• Phylum Bryozoa

• Phylum Mollusca

• Phylum Annelida

• Phylum Arthropoda

• Phylum Echinodermata

• Phylum Chordata

Phylum Chordata

• Subphylum Urochordata– Class Ascidiacea (tunicates)– Class Thaliacea (salps, gelatinous

thaliaceans)

• Subphylum Vertebrata – this week.

All chordates possess at some time during development a notochord (made of cartilage) along midline of body, below a hollow dorsal nerve cord, as well as a postanal tail and pharyngeal pouches.

Subhylum Vertebrata

• Class Agnatha (jawless fish)

• Class Chondrichthyes (cartilaginous fish)

• Class Osteichthyes (bony fish)

• Class Reptilia (reptiles)

• Class Aves (birds)

• Class Mammalia (mammals)

Subphylum Vertebrata

• Class Agnatha (jawless fish)

• Class Chondrichthyes (cartilaginous fish)

• Class Osteichthyes (bony fish)

• Class Reptilia (reptiles)

• Class Aves (birds)

• Class Mammalia (mammals)

Features of Vertebrates

• Postanal tail, pharyngeal pouches (chordate)

• Vertebral column (develops from notochord; segmented)

• Specialized sensory organs

• Brain at anterior end of nerve cord

• Closed-loop circulatory system (heart, arteries, capillaries, veins)

• Myomeres (muscle segments)

Marine Fish

• Agnatha – hagfish (most primitive), lampreys– [body fluids isotonic to seawater; 30-50% in other vertebrates]

• Chondrichthyes – sharks, skates, rays– [large: <20cm to >15m]

• Osteichthyes – bony fishes: tarpon, eels salmon, sardines, lanternfish, toadfish, flying fish, seahorses, pipefishes, scorpionfishes, sculpins, basses, groupers, snappers, barracudas, wrasses, tunas, triggerfishes, molas, pufferfish, etc.

– [bone stronger and lighter than cartilage; small size, diverse adaptations and habitats]

Body shape specialization:

• High maneuverability (e.g., butterflyfish)

• Rapid acceleration (e.g., barracuda)

• Efficient cruising (e.g., tuna)

• Eating methods:– Ramming (e.g., sharks)– Biting (e.g., triggerfish)– Sucking (e.g., butterflyfish)

Marine Reptiles

• Snakes (61 species of true sea snakes, most of them highly venomous)

• Turtles (7 species of sea turtles)

• Iguanas (1 species of marine iguana, Galapagos Islands)

• Estuarine environments: additional snakes, caymens, alligators, crocodiles)

Marine Birds

• Feathers and front appendages adapted for flight

• Species: range of dependence on marine environment – Ducks, geese, coots– Shorebirds: herons, stilts, sandpipers– Albatrosses, petrels, gannets, pelicans, gulls, terns, murres– Penguins

• Birds and Mammals are true homeotherms

Marine Mammals

• Order Carnivora– Pinnipeds: Seals, sea lions, walruses, sea

otters– Polar bears

• Order Cetacea– Whales, dolphins, porpoises

• Order Sirenia– Manatees, dugongs

Characteristics of mammals

• Viviparous• Body hair• Milk-secreting mammary glands• Specialized teeth• Separate reproductive / digestive tract openings

[other vertebrate groups oviparous or ovoviparous, and have a cloaca]

Modern cetaceans

• Suborder Mysticeti – [baleen whales] lack teeth; have rows of baleen projecting from upper jaw to filter-feed

• Suborder Odontoceti – [toothed whales] smaller; specialized teeth help capture slippery fish, squid, other prey

Links

• Basic background on marine mammals

• Pinniped photo gallery

• Cetacean photo gallery

• National Marine Mammal Lab, Cetacean Assessment Program

• Sea Otter Evolution and Adaptations