Morning at the bottom of the sea

Today’s morning name surfaced from the depths of the ocean: benthic, especially in the phrase benthic worm. No, I don’t know why.

(Insert here a note about the salty fellow Benthic Worm, a denizen of the abyssal plain, who bristles at the epithet dirty.)

The story in a muddy capsule, from NOAD:

noun benthosEcology the flora and fauna found on the bottom, or in the bottom sediments, of a sea, lake, or other body of water. [adj. benthic] ORIGIN late 19th century: from Greek, ‘depth of the sea’.

Expanded in Wikipedia:

Benthos is the community of organisms that live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.

Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column. The pressure difference can be very significant (approximately one atmosphere for each 10 metres of water depth).

Because light is absorbed before it can reach deep ocean-water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains the benthic food chain; most organisms in the benthic zone are scavengers or detritivores.

The term benthos, coined by Haeckel in 1891, comes from the Greek noun βένθος “depth of the sea”. Benthos is also used in freshwater biology to refer to organisms at the bottom of freshwater bodies of water, such as lakes, rivers, and streams

… Macrobenthos comprises the larger, more visible, benthic organisms that are greater than 1 mm in size. Some examples are polychaete worms, bivalves, echinoderms, sea anemones, corals, sponges, sea squirts, turbellarians and larger crustaceans such as crabs, lobsters and cumaceans.

… Meiobenthos comprises tiny benthic organisms that are less than 1 mm but greater than 0.1 mm in size. Some examples are nematodes, foraminiferans, water bears, gastrotriches and smaller crustaceans such as copepods and ostracodes.

… Microbenthos comprises microscopic benthic organisms that are less than 0.1 mm in size. Some examples are bacteria, diatoms, ciliates, amoeba, flagellates.

Most of these creatures are familiar to me, even the tiny ones, which I used to study under a microscope when I was a kid — in local pond water. But polychaetes were new. From Wikipedia:

The Polychæta, also known as the bristle worms or polychætes, are a paraphyletic class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. As such, polychaetes are sometimes referred to as bristle worms. More than 10,000 species are described in this class. Common representatives include the lugworm (Arenicola marina) and the sandworm or clam worm Alitta.

Polychaetes as a class are robust and widespread, with species that live in the coldest ocean temperatures of the abyssal plain, to forms which tolerate the extremely high temperatures near hydrothermal vents. Polychaetes occur throughout the Earth’s oceans at all depths

I’ll bet you didn’t know that polychaetes now have their own day on the calendar: July 1st. Established by the University Museum of Bergen (on the west coast of Norway), in honor of invertebrate zoologist Kristian Fauchald:

(#1) [the museum’s caption:] Some of the wonderful worms that were collected during #AnnelidaCourse2017. From top left: Glyceridae, Syllidae, Spionidae, Cirratulidae, Phyllodocidae, Scalibregmatidae, Flabelligeridae, Polynoidae, Serpulidae and Cirratulidae (photos & montage: K.Kongshavn)

Ah, then I recalled another group of benthic worms. From Wikipedia:

Priapulida (priapulid worms, from Gr. πριάπος, priāpos ‘Priapus’ + Lat. –ul-, diminutive), sometimes referred to as penis worms, is a phylum of unsegmented marine worms. The name of the phylum relates to the Greek god of fertility, because their general shape and their extensible spiny introvert (eversible proboscis) may recall the shape of a penis. They live in the mud and in comparatively shallow waters up to 90 metres (300 ft) deep. Some species show a remarkable tolerance for hydrogen sulfide and anoxia. They can be quite abundant in some areas. In an Alaskan bay as many as 85 adult individuals of Priapulus caudatus per square meter has been recorded, while the density of its larvae can be as high as 58,000 per square meter

Previously on this blog, my 8/5/12 posting “Snakes, worms, fish, clams, slugs”, where Priapulus figures prominently:


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