Page 183 - (DK) Ocean - The Definitive Visual Guide

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OOZE-FORMING ZOOPLANKTON
These radiolarians are single-celled
planktonic animals. After death, their
skeletons, made of silica glass, sink to
the seabed, accumulating as sediments.

Feeding on the Ooze

Biogenic Oozes The “snow” of calcareous and siliceous remains from the upper
levels accumulate on the ocean floor, providing the main source
Biogenic sediments are formed mainly from of food for animals living in or on the sediments. Bacteria live in
the shells and skeletons of microscopic the ooze, where they break down organic remains. In turn, they—
organisms that sink to the seabed after death. along with other organic matter —are consumed by multitudes of
The decaying remains of larger organisms, such tiny foraminiferans. Nematodes, roundworms, isopods, and small
as molluscs, corals, calcareous algae, and starfish, bivalve mollusks live and feed in the mud. Brittlestars feed on the
add to this accumulation. Oozes are calcareous COCCOLITHOPHORE ooze by sweeping food off its surface with their arms. Sea pens,
When this coccolithophore
if derived from the calcium carbonate shells dies, its platelets will add crinoids, and glass sponges, which are anchored to the seabed,
of foraminifera, pteropods, and coccolithophores to the calcareous ooze. filter organic particles from the water column.
(microscopic algae), or siliceous if derived from the tube feet enable animal
silica shells of single-celled radiolarians or diatoms. to traverse sediment
SEA CUCUMBER FEEDING while foraging
Because silica dissolves rapidly in seawater, siliceous
Sea cucumbers wander widely
oozes only build up beneath zones of over the seabed, sucking up the
high primary production. As calcareous sediment and then extracting
shells and skeletons sink, they reach a its organic content. OCEAN ENVIRONMENTS
depth (around 15,000 ft/ 4,500 m) where the
water becomes more acidic; this, combined with
pressure, means calcareous remains are dissolved
rapidly in seawater at depth. Calcareous oozes
FORAMINIFERA
therefore occur only above this “calcium carbonate
The tiny shells of dead
compensation depth,” beneath which the seabed foraminiferans add to
consists mainly of terrigenous red clays. the biogenic oozes.