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Selected Adaptive Strategies: Bioluminescence. Fishes - important nektons Many are deepsea predators Need their own light to attract prey … to attract mates luciferin + luciferase. More Nekton Strategies. predator/prey must be swift and efficient swimmers move swiftly to eat
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Selected Adaptive Strategies:Bioluminescence • Fishes - important nektons • Many are deepsea predators • Need their own light to attract prey • … to attract mates • luciferin + luciferase
More Nekton Strategies • predator/prey • must be swift and efficient swimmers • move swiftly to • eat • avoid being eaten. • Thus fish have evolved to maximize their ability to move through water.
Caudal (Tail) Fins•most important for speed • flared to increase vertical thrust(Figure 9-22)
ROUNDED fin (e.g., flounder)very flexible, slow-speed manuevering
TRUNCATE fin (e.g., angel fish)somewhat flexible, manuevering
FORKED fin (e.g., goatfish or herring)somewhat flexible, manuevering
LUNATE fin (e.g., blue marlin or tuna)very rigid, no good for manuevering,built for pure speed
HETEROCERCAL fin (“uneven tail)• most of mass & surface area in upper part to produce lift• pectorals balance to aid liftlimits manueverability
Caudal Fins • rounded • very flexible, manuevering • truncate & forked • somewhat flexible, manuevering • lunate • very rigid, propulsion • heterocercal • “uneven tail” for lift and propulsion
Built for Speed • speed related to body length • 4-foot yellowfin tuna, 46 mph • 13-foot bluefin tuna, 90 mph (theoretically) • 9-foot porpoise, 25 mph • 30-foot killer whale, 34 mph
Squid:• traps water in mantle and forcefully jettisons it from siphon in head
• active predator of fish• arms to capture• tentacles to bring to beak• both lined with suckers
Colossal Squid CapturedWellington, NZ, April 2003330 pounds - 16 feet long