Water's ability to absorb heat and transmit light buffers many marine habitats from extreme environmental conditions.

Still, certain habitats are characterized by extremes in temperature, light, and pressure.

Deep sea habitats are characterized by low light, high pressure (> 400 atmospheres), cold temperatures (1-4 °C), little current, and fine (soft) sediments.

On a large scale, these habitats are extremely stable, with little change in conditions for extended periods of time

Despite this stability, soft bottom habitats are turned over regularly by burrowing and feeding behaviors, creating local spatial heterogeneity.

Soft sediments will foul suspension feeders, so detritivores dominate.

Echinoderms, mollusks, brachiopods, and fish are common members of the community

Though nutrients are not limiting, the lack of light keeps primary productivity low.

Organic material is in short supply and microbial activity is low

Low microbial activity limits decomposition and consumption of oxygen

High pressure, cold temperatures, or adaptations to low resource availability may be responsible

Food is sparse, but uniformly distributed, so organisms are often spread out.

Adaptations include the ability to consume large prey, when encountered.

Many deep sea marine organisms are simultaneous hermaphrodites because the probability of encountering a conspecific is low.

 

Deep sea vents represent an oasis of biological diversity in the otherwise uniform benthos

Two kinds of vents:

"Hot smokers" often release sulfide compounds

Common in volcanically active regions such as the Pacific and the mid-Atlantic ridge

Cold seeps often release methane (best known are off the continental slope near Florida).

These vents often support unique communities of marine organisms, including large limpets, clams, mussels and 3 m long worms!

Mutualism between chemosynthetic bacteria and these benthic organisms permits this biodiversity

In most cases, bacteria oxidize sulfide released from the vents, providing high levels of primary productivity

Adaptations for exploiting the energy of these bacteria include

Spongy tissues or organs (trophosome) that contain high concentrations of bacteria (some lack a real gut)

Gills that can hold bacteria

Specialized hemoglobin that can bind and transport sulfide to bacteria laden tissues.

Despite their patchy occurrence in the deep sea, larval dispersal appears to be common and widespread

Microbial symbiosis also appears to be important in other, less common, communities including decaying wood (contains nitrogen-fixing bacteria) and oil-rich sediments (hydrocarbon consuming bacteria).

Some examples of deep sea biodiversity

The gulper eel, Saccopharynx harrisoni , has a huge mouth and sharp teeth that allows it to swallow animals larger than itself. They can reach a length of at least four feet with a whip-like tail with a light at the tip.

The deep sea squid, Heteroteuthis dispar, is a three-inch long deep sea squid that can expel a bioluminescent ink to confuse predators.

The vampire "squid", Vampyroteuthis infernalis, has ten arms but is neither squid nor octopus. Two of its arms are sensory filaments that withdraw into pockets. This organism has the largest eyes relative to body size.

Click here to see what this thing looks like

Some links to "Deep Sea" web sites

Whaling Impacts on Deep-Sea Biodiversity

Various links to deep sea sites

 

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