The Abyss and Hydrothermal Vents

This set of vocabulary flashcards covers the biology, environmental conditions, and specialized organisms of the deep-sea abyss, hydrothermal vents, and cold seeps.

Enypniastes

A deep-sea holothuroid which swims and uses its tentacles around its mouth to scoop up mud from the surface of the deep sea.

Features of Deep Sea Habitats

Environmental conditions characterized by no light, high pressure, cold temperatures, slow water movement, and low biomass ($1\%$ of coastal habitat values).

Deposit Feeders

Organisms that feed on organic matter in the sediment, making up $80\%$ of deep-sea inhabitants.

Sea Pig

A specific type of echinoderm, mentioned as a successful deep-sea organism found in MBARI images.

Physiological Adaptations of Deep Sea Fauna

Include slow growth rates, late maturation with few eggs, low metabolic rates, high water content, and low protein content.

Hydrothermal Vents

Undersea hot springs associated with mid-ocean ridges, located below $2000\,m$ with water temperatures ranging from $8$ to $390^{\circ}C$.

Vent Fluid Chemistry

The water is anoxic, acidic, and contains toxic but energy-rich hydrogen sulphide ($H_2S$ or $HS^-$ ions).

Riftia pachyptila

Vestimentiferan worms that can grow $1.5\,m$ in $18$ months; they lack a mouth or gut and rely on a trophosome containing bacteria.

Calyptogena magnifica

A giant clam with a reduced mouth and gut; it features large gills with high blood volume and takes in $H_2S$ through its foot.

Chemosynthesis Equation

$$12H_2S + 6CO_2 \rightarrow C_6H_{12}O_6 + 6H_2O + 12S$$

Seeps

Habitats occurring along continental shelf margins or high organic matter areas where methane, hydrogen sulphide, and hydrocarbons rise from the sediment.

Methane Ice Worms

Organisms inhabiting white methane hydrate in the Gulf of Mexico that eat chemoautotrophic bacteria.

Asphalt Seep

Geological features where heavy petroleum seeps from the ocean floor and hardens.

Brine Pools / Lakes

Highly salinic, toxic underwater lakes on the ocean floor that are $3\text{ to }8$ times saltier than surrounding seawater.

Trophosome

An internal organ in vestimentiferan worms like Riftia pachyptila that contains symbiotic bacteria used for energy production.

Infauna

Deep-sea animals that live within the sediment, often characterized by small size or specific feeding gut adaptations.

Epifauna

Animals that live on the surface of the ocean floor, such as brittle stars, sea cucumbers, and sea stars.