Benthos

• Benthos are creatures that live on, near, or in the bottom of the ocean floor.

• There is a huge variety of benthos and what you find depends on what the bottom is made of.

Benthos, cont’d• Seaweeds are primary producers found

attached to rocky bottoms. There are red, brown and green seaweeds.

• Some seaweeds have air bladders so that they can float toward the sunlight.

• Several species are harvested to eat or extract seaweed products (algin, carrageenan) which are used as thickening agents in foods such as ice cream, pudding, chocolate milk

Benthos, cont’d• Creatures that attach to the bottom are

barnacles, mussels, periwinkles

• Creatures that live near the bottom are crabs, lobsters, sea stars, sea urchins, and several species of fish including skates and flounder.

• Creatures that burrow in the bottom are clams and worms

Common Benthos

Benthos, cont’d• Benthos in the intertidal zone must cope

with an incredible range of conditions - temperature, salinity, humidity

• Many of these creatures have some means of avoiding dessication (drying out). Periwinkles and barnacles can close off their shells to prevent water loss, clams burrow into the mud, and seaweeds have a waxy coating to resist drying.

Deep Sea Benthos

• Challenges of living in the deep sea are:• Low availability of food

– No light, no photosynthesis

– Falling remains of dead organisms

• Low (0-2°C), constant temperature

• High pressure (400-500 times atmospheric)

Deep Sea Benthos, cont’d

• Characteristics of many deep sea benthos are:– low activity levels

– slow growth; long lives

– low population densities but high species diversity

Deep Sea Benthos, cont’d

• Some common adaptations are:– opportunistic deposit feeders

– high water content in their bodies to deal with the pressure

– bioluminescence to attract food and mates

– large eyes and big mouths

Deep Sea Benthos

Gulper Eel

Anglerfish

Anglerfish

Viperfish

Deep Sea BenthosFangtooth

Hydrothermal Vents

• Areas where geologic-heated water (400-600ºC) and gases are released from the ocean floor

• Basis of life around deep sea hydrothermal vents is chemosynthesis rather than photosynthesis.– chemical energy rather than sunlight

– bacteria rather than plants or algae are the primary producers.

Hydrothermal Vent Benthos

Clams

Tube Worms