calcareous foraminiferan Cibicides refulgens

Cibicides refulgens is found in Antarctica from 10 to 640 meters depth [3]. C. refulgens prefers hard substrates (shown here attached to a small limpet and to an erratic glacial boulder, at Explorers Cove, New Harbor) [1]. C. refulgens is often found living on various invertebrates, including the Antarctic scallop Adamussium colbecki [1,2].

For those found in association with the Antarctic scallop Adamussium colbecki, C. refulgens has three feeding modes useful for survival in a food-scarce (oligotrophic) and seasonal environment: grazing algae and bacteria living on the surface of the scallop shell; suspension feeding through a pseudopodial net deployed from a superstructure of agglutinated tubes extending from the foram's calcareous test; and, parasitism by eroding through the scallop shell, and using free amino acids from the scallop's extrapallial cavity [2].

Here's a closer view of Cibicides refulgens.

A foraminiferan is a unicellular organism, characterized by long, fine protrusions (pseudopodia) extending far away from their cytoplasmic body which is encased within a test or shell. There is always one nucleus but there may be a stage with multiple nuclei early in asexual reproduction. Foraminifera are a class within the kingdom Protista or Protoctista (depending on author's taxonomic preference) which encompasses eukaryote organisms like algae, protozoa and flagellate fungi. Foraminifera are almost entirely marine and are one of the most abundant marine invertebrates, playing a major role in the marine environment. Bottow-dwelling (benthic) foraminiferans occur in most marine environments, particularly in deepsea and outer continental shelf muds.

Foraminiferans as a group may eat live food (bacteria, unicellular algae, especially diatoms, other protozoa, and small crustaceans such as copepods which are snared in their pseudopodia) or dead material (dead organisms, organic-rich grains including fecal pellets, particulate organic detritus, and colloidal organic molecules). These broad food preferences make them ideally adapted to the benthic environment.

1: Sam Bowser, personal communication, 2000; 2: Biological Bulletin 173(1), 136-159, 1987; 3: Tethys 6(3):631-653, 1974

Text ©Peter Brueggeman. Photographs ©Robert Sanders (Sam Bowser/S043 archives). Photographs may not be used in any form without the express written permission of Robert Sanders (Sam Bowser/S043 archives).