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Fishes – Biology Migration Generally related to feeding and/or reproduction Diel Horizontal Ex: Grunts (day on reef, night feeding in seagrass beds) Vertical Ex: Mesopelagic fishes Large Scale Ex: Skipjack tuna feed in Eastern Pacific, spawn in Western and Central Pacific.
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Fishes – Biology • Migration • Generally related to feeding and/or reproduction • Diel • Horizontal • Ex: Grunts (day on reef, night feeding in seagrass beds) • Vertical • Ex: Mesopelagic fishes • Large Scale • Ex: Skipjack tuna feed in Eastern Pacific, spawn in Western and Central Pacific
Fishes – Biology • Migration • Anadromous • Spawn in fresh water • Spend most of life in ocean • Ex: Salmon (seven species) in Pacific Ocean • Spawn in shallow areas of rivers/streams • Semelparous (adults die after spawning) • Young migrate downstream to ocean after 0-5 years • Spend 3-7 years in ocean before returning to home stream • Homing behavior enabled by olfactory imprinting • Important source of nutrition for wildlife, forests
Fishes – Biology • Migration • Catadromous • Spawn in ocean • Spend most of life in fresh water • Ex: Eels (16 species) in Atlantic Ocean • Spawn in Sargasso Sea (400-700 m or deeper) • Semelparous • Eggs hatch into leptocephalus larvae • Larvae spend a year or more as plankton then undergo metamorphosis into juveniles • Adults spend 10-15 years in fresh water before migrating to Sargasso Sea to spawn
Tetrapods • Amphibians (Amphibia) • Terrestrial, freshwater • Live near/in water; some species entirely aquatic • Reproduce in water; most with external fertilization • Ectothermic • Reptiles (Reptilia) • Terrestrial, “freshwater”, marine • Adapted to life out of water; some species entirely aquatic • Ectothermic • Birds (Aves) • Terrestrial • Some species dependent on aquatic systems • Endothermic • Mammals (Mammalia) • Terrestrial, “freshwater”, marine • Some species entirely aquatic • Endothermic
Evolution of Limbs Tiktaalik Tiktaalik Sea-Land Transition evolution.berkeley.edu/evolibrary/article/evograms_04
Amphibians • Urodela (salamanders, newts) • Terrestrial, aquatic: ~550 species • Retain tails as adults (paedomorphic character) • Fertilization usually internal • Anura (frogs, toads) • Terrestrial, aquatic: ~5400 species • Possess tails as juveniles; not in adults • Fertilization usually external • Apoda (caecilians) • Terrestrial (mostly), aquatic: ~170 species • Legless (secondary) • Fertilization internal