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Basic Ecology

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

Selected Adaptive Strategies: Fish Bioluminescence

- 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.

• Statistics - They may be up to 1.2m (4ft) long, but most are much smaller.
• Physical description - Inky black deep sea fishes, that live at extreme ocean depths, characterised by huge mouths, enlarged eyes and the presence of luminous organs on some or several parts of the body used to attract either prey or potential mates. Often bizarre in form, anglerfishes have small gill openings and limblike pectoral and pelvic fins. Many female anglers have a modified dorsal fin which varies in length according to species. This is almost always luminous, with a simple to ornate lure. The bioluminescence is produced by bacteria housed in the lure, though how they get there is unknown. In some species there are also other luminous organs. Unlike other anglers, the deep sea anglers lack pelvic fins and swim about, though feebly, rather than live on the bottom.
• Habitat - Live in depths of up to 4000m.
• Diet - Deep sea anglers prey on various fishes and invertebrates. Some have been known to swallow prey larger than themselves.
• Behavior - Angler fish lure prey within reach by dangling their extended dorsal fin spines as bait, hence the name. Other traits represent evolutionary adaptations to the extreme pressure, cold and darkness of the deep sea environment. Some species are notable for the fact that the males are very small in comparison with the females and live as permanent parasites on their mates, perhaps because locating each other initially is so difficult in the dark conditions. In these species, the male attaches himself, by biting, to the body of the female. His mouth fuses with her skin and the bloodstreams of the two fishes become connected, the male thereafter remaining totally dependent on the female for nourishment.

Gulper/Pelican eel - Eurypharynx pelecanoides

• Statistics - This species of gulper eel grows up to 60cm (2ft), although some other species can be up to 2m.
• Physical description - Gulpers have a long, whip-like tail and an enormous mouth, which is loosely-hinged so that it can be opened wide enough to swallow animals much larger than themselves. The gulperÕs stomach can also expand to accommodate any large meal that it consumes. They are black and have long whip-like tails.
• Distribution - They inhabit all temperate and tropical seas.
• Habitat - Gulper eels are found at depths of 500-7,500m.
• Diet - Food is scarce thousands of metres down, so itÕs important to be able to eat whatever comes along. This species has poorly developed teeth, so mainly eats small crustaceans, but will also feed on fish and cephalopods.

Hatchetfish - Sternoptychidae spp.

• Statistics - Size varies between species, but they are no larger than 10cm (4in).
• Physical description - Small, flat hatchet-shaped marine fish whose abdomen forms a keel. Shiny silver in colour with large, sometimes telescopic eyes. Very deep, laterally compressed bodies, thin tails and bioluminescent organs along their lower sides. They have tubular eyes which point upwards enabling them to search for prey against any light from above.
• Distribution - Warm and temperate regions worldwide.
• Habitat - Inhabit the deep ocean at depths of about 200-1,000 m (650-3,000 ft).
• Behavior - Uses bioluminescent organs along its sides, probably for species and sex recognition as well as for camouflage, as the silhouette of the fish is broken up, making it hard for predators to see them from below.
• Reproduction - Breeding takes place during a short period at the beginning of the rainy season. The brood size is relatively small.

More Nekton Strategies

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.)

Surface drag

Form drag

Turbulent drag

Fish Bodies

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

Fins

truncate & forked:
somewhat flexible, manuevering

lunate:
very rigid, propulsion

heterocercal:
uneven tail for lift and propulsion

Built for Speed

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

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

Squid

active predator of fish

arms to capture

tentacles to bring to beak

both lined with suckers

They Exist! at 20-60 feet long!

Summary

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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