Monday, February 29, 2016

Small and smaller

Near the bottom of every marine food chain, we find copepods. In my tank, the anemones, the oysters, and the barnacles all depend on them. And I take them for granted; they're the flecks that I have to clean out of photos, the speeding speckles on the glass, getting in the way of what I wanted to see.

I went looking for them last night, instead.

The red algae provide a nice contrast, and give the copepods something to do rather than race around. This algae is growing on the big anemone's trunk. One of her tentacles is visible between the leaves.

A darker red seaweed, growing on a stone. Some, at least, of the speckles are copepods. Others are bubble; this plant collects a lot of bubbles.

Very tiny female copepod, with her egg sac. Most copepods have one red eye.

A different species, with black markings. The blue globe is her egg sac.

Another blue-green egg sac.
Copepods on the glass beside the anemone. I scrubbed this glass only three days ago, and it's already populated with assorted algae and unidentified "stuff". The copepods are busy eating it all.

One copepod on a relatively clean bit of glass. View from the underside, although they're so tiny, the innards show through from either side. Copepods without egg sacs are either males or juveniles. The males are usually smaller than females.

These were all very small copepods. Others in the tank, much more active, are twice the size. Their females carry double egg sacs, off to the sides, as in this photo from 2010:

This copepod is about 1 mm. long.

Planktonic copepods are important to global ecology and the carbon cycle. They are usually the dominant members of the zooplankton, and are major food organisms for small fish such as the dragonet, banded killifish, whales, seabirds, alaska pollock and other crustaceans such as krill in the ocean and in fresh water. Some scientists say they form the largest animal biomass on earth. ...
Because of their smaller size and relatively faster growth rates, and because they are more evenly distributed throughout more of the world's oceans, copepods almost certainly contribute far more to the secondary productivity of the world's oceans, and to the global ocean carbon sink than krill, and perhaps more than all other groups of organisms together. (Wikipedia)
The average adult right whale consumes about a ton of food a day, eating billions of tiny crustaceans called copepods that are packed with protein and calorie-rich oils. (Woods Hole Oceanographic Inst.)

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