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Marine Ecology: Adaptive Strategies

Basic Ecology

- factors regulating the distribution and abundance of organisms in the ocean.

- influence of physical and chemical parameters on organisms in the various ecosystems that constitute the ocean.

Selected Adaptive Strategies: Fish Bioluminescence

- Fishes - important nektons

- Many are deepsea predators

- Need their own light to attract prey

- ...to attract mates

- photophores - light-producing or light-reflecting cells on the fish

- luciferin + luciferase - chemical reaction in the fish

Blue Planet Video: The Deep

bioluminescence = the emission of light from an organism. Bioluminescence occurs in a range of life forms. It is a direct and efficient conversion of energy derived from a chemical reaction in the rganism into light energy, giving off no heat in the process. Bioluminescence is used variously as a protection mechanism or in the mating process.

For example, some deep sea fishes lure prey with luminescent organs, or use light to disguise their actual shape. Squid squirt out a luminous ink to confuse their enemies and make an escape. Some species use it for recognition of like species. Fireflies "flash" to attract the attention of females who then signal back and the male uses the interval between the flashes to identify and seek out the female.

Some organisms featured in the video:

Angler fish (deep sea) - Ceratioidei spp.

Gulper/Pelican eel - Eurypharynx pelecanoides

Hatchetfish - Sternoptychidae spp.

More Nekton Strategies

As seen in the video, many fish are predators which means that they must be swift and efficient swimmers.

Fish that are prey must also be able to move swiftly to avoid being eaten.

Thus fish have evolved to maximize their ability to move through water.

Nekton Strategies (Cont.)

Drag that reduces the efficiency of swimming can be overcome by minimizing:

Surface drag

Form drag

Turbulent drag

Fish Bodies

Caudal (tail) fin most important for speed flare to increase vertical thrust 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 lift limits manueverability


very flexible, manuevering

truncate & forked:
somewhat flexible, manuevering

very rigid, propulsion

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

Cruisers (red muscle tissue)
- "slow-twitch" endurance athletes

Lungers (white muscle tissue)
- "fast-twitch" sprinters


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

They Exist! at 20-60 feet long!


The oceans are subdivided into 2 major regions the pelagic and benthic provinces which in turn are subdivided into smaller subdivisions.

Marine organisms are classified into 3 major groups based upon lifestyle, the plankton, nekton, and benthos.

Marine organisms show a tremendous diversity of adaptations that enable them to live in the various parts of the ocean.

Ecology deals with the interrelationships among organisms and their physical and chemical surroundings.

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