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Oddities, Debris and Decay

Much of a plankton sample consists of variable amounts of debris, sediment and dead material. After a period of strong wind stirring up the Haven these will increase. While solid particles like mineral grains allow tiny organisms to attach, e.g. the diatom Delphineis and stalked ciliates, much of this Dead Organic Matter (DOM) is essential for the ecosystem and the microbial loop. Bacteria and fungi are at the base of this loop. Free-living bacteria can be quite visible as tiny dark dots moving slowly in the background even under x400 magnification. With the particulate DOM they form dense aggregates of material. The bacteria, in turn are consumed by nanoflagellates. Rising up the food web these (and bacteria) are consumed by species covered in these samples, namely, the protists like the ciliates, especially tintinnids. The ciliates are at the top of the microbial loop. In water systems a considerable amount of dissolved organic mater exists and feeds into this loop. This is "leakages" from diatoms and other organisms.

Much debris can be identified while other structures and species elude ID.
Unknown material

Mineral debris x400 DIC lighting


A possible type of nanoflagellate. These are part of the nanoplankton, beyond the realms of my Haven sampling but they regularly appear. Very small (up to 20 microns) this one is magnified about x1000. Very active this one is feeding close to a DOM aggregation

Shed exoskeleton legs of acorn barnacle

The large, cast exoskeleton of barnacle limbs. Abundant in all samples, this net of hairs and limbs trap considerable amounts of other debris was well as diatoms. When looking under the microscope they are always useful places to look for tiny organisms feeding like ciliates.

dead copepod decay bacteria and ciliates feeding

This dead copepod is full of bacteria (black dots) but the most obvious group of organisms are the large round ciliates inside feeding on the microbes.

sponge spicule

Spicule of a sponge

Shed exoskeleton crustacean limb

Part of a shed exoskeleton of a crustacean limb

clunio marinus head capsule chironomid fly

Possible head capsule of a marine chironomid fly, Clunio marinus, that lives in rockpools

A bristle from a Sabellarian worm

Pollen grain, a common occurence

A barbed spine

Skeletal plate of either starfish or sea cucumber larva

Stellate hair from a land plant

Unknown species and Material

Any ideas gratefully received

1. Often very abundant, violently wriggling, initially thought to be an embryo hatching, possibly tunicate. Currently, completely baffled.

Size: 80 microns



Size: 200 - 500 microns plus. Variable, occasionally common in the summer from the open sea


Size: 500 microns. Found only once in April 2023. Stiff movement, highly ciliated especially on the inside of the curl.


Left. Found only once. Active cilia movement. Size: 200 microns? A Ditylum diatom below it


Found very occasionally in winter or spring. Diatom like? Size: 50 microns


Found at random times. Cyst? Size: 40 microns

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