sea anemones -- 9/14/22
Today's selection -- from Life Between the Tides by Adam Nicolson. A fight among the sea anemones:
"At the western edge of the pool on Rubha an t-Sasunnaich, where it shallows towards one of the volcanic dykes, the anemones were proliferating all summer. In some parts by September there were more than 300 of them in a square yard, all sizes, none quite touching, but each gently sifting from the surrounding water the food they needed.
"In other places, I had found the wavering grey-yellow arms of the snakelocks and, in cracks and crevices further down the tide, the green blotched strawberry anemones, their bodies stuck with bits of sand and coralline flakes, the variegated tentacles of a dahlia anemone and some white elegant ones, as bright as candles.
"Here in the pool, they were all the usual beadlets, Actinia equina, the most common of all, slightly various in their colours but named after the ring of little blue stinging cells or acrorhagi -- a Victorian Greekism meaning 'high berries' -- arranged as a necklace inside the lip of the columnar body. The acrorhagi are usually invisible when the main tentacles are up but appear as the anemone folds down into itself when conditions are not good -- if the tide has dropped away, or the salinity has fallen or the temperature risen.
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| Beadlet anemone |
"Otherwise, these simple animals merely wave their tentacles in the passing water like flowers in sunlight. That is why they are called anemones, named only in the late eighteenth century from their resemblance to the flowers of wood and meadow.
"Brush your fingers through them, as the Australian poet Gwen Harwood has said, and you will find your 'fingers meet some hungering gentleness'. The little stings the anemones give you with these red tentacles do not hurt, but feel more like a kind of stickiness than an attack.
"Some anemones are sexual, and release their sperm and eggs into the surrounding water, relying on some chance union, but these beadlets reproduce asexually, making tiny, genetically identical versions of themselves which emerge into the surrounding world as their fully functioning progeny. If you ruffle through them enough, you will find tiny anemone reproductions spilling out on to your fingers, each baby blob of life looking in a magnifying glass like a raspberry mousse.
"They are among the simplest animals, not very different from their long-distant ancestors whose rare soft-body fossils have been found in deposits more than 500 million years old. They have no centralised nervous system, no brain, no organs of excretion -- whatever needs to come out as waste is ejected through the same tentacle-surrounded hole by which the food went in. Their muscles and nerves are simpler and less organized than in almost any other animal. They have no skeleton; water pressure alone, held tight within the body cavity by the mouth closing over it, provides their solidity. Foods are dissolved by simple digestive enzymes into the chemical constituents that the anemone can absorb.
"They are scavengers, eating the dead and broken parts of animals that float past in the tide. High up near the grass, they ingest plenty of dead midges and mosquitoes. Further down, it is little sandhoppers, parts of prawns, crab megalopses and lots of tiny unattached young mussels: in short, most of the characters that have populated this book. A large one has been seen to swallow a smelt six inches long. Some Irish scientists have tested the anemones' appetite for something more, popping rather large mussels into the oral cavity to see what happened. The anemones accepted the offering easily enough and the mussels disappeared inside them while the scientists waited. Up to two hours later, the complete and uninterfered-with mussel came back out. The anemone had been unable to get access to the meat. When the scientists cut the muscle by which the bivalve kept itself closed, there was a different outcome. Very nearly nine hours later, the shells were spat out by the anemone, the meat of the mussel having entirely disappeared.
"I collected some from the shallows at the edge of the pool. They are easy to peel off, if you lift them gently and carefully from the rocks they are stuck to. They come away almost exactly like Post-its, closing their tentacles with the disturbance but otherwise untroubled. The bodies of these Actiniae in the pool are red all the way down, the colour just paling at the foot. Some others that I found at the far end of the headland, and on rocks lower in the tide, had a blue line around the foot of their columnar bodies. Both were beadier anemones, but of two different morphs, each living in slightly different environments.
"In separate lidded boxes filled with seawater, I took them back to the aquarium in the house and left them to acclimatize for an hour or so. By the time I went to look, things had started to happen. One of the Bluefoots had been in a fight and had suffered in it, with pale wounds from its enemy's attack cells, the acrorhagi, stapled down one side of its body. An attacking anemone leaves part of the acrorhagus on the body-column of its adversary, continuing to deliver its toxins even after the fight is over. The flesh around these 'acrorhagus peels' had crumpled and puckered with the damage.
"The Bluefoots had now moved to another stone where again it found itself next to a Redfoot. The two of them were meeting each other with their outer tentacles. Redfoot was bigger, its base spread wide and oddly warty, with its tentacles fully displayed, while Bluefoot looked less happy, tentacles retracted, a little inward (see second colour place section).
"Soon, though, Bluefoot made its defensive move and started to lean in towards the Redfoot enemy, which reacted at first by pulling back some of its outer tentacles. It was a temporary withdrawal. Minutes afterwards, Redfoot pulled itself up to its greatest height, reshaping its whole body and contorting its blue attack cells into a tiara of violence towards Bluefoot, leaving its upper red tentacles withdrawn, hooked and clawed. It was a ferocious display of aggression, of selfhood, of one being set against another.
"Toxic darts spurted from Redfoot's acrorhagi into Bluefoot's body, sticking into the flesh, standing out from it like arrows in a target and leaving white threads wrapped around the enemy's waist. For the second time Bluefoot gave up the fight, detaching itself from the rock and starting to drift past and away from its aggressor.
"This attempt to escape re-summoned all the defensive aggressive instincts in Redfoot. As Bluefoot rolled over and past it, revealing the pale grey underside of its foot, Redfoot once again came up into its flamboyant, menacing attack form. Bluefoot was now in a hopeless situation, upside down and defenceless next to the fierce, charged presence of its enemy.
"As its crumpled body drifted past, Redfoot, still wearing its extraordinary erect war-corona, bent over and down, on to the spot Bluefoot had just vacated, and deposited there a single tiny new anemone, an asexual done of itself, generated and brooded within its body cavity, placed to occupy the neighbouring area of rock that would now become part of its own clonal territory.
"Bluefoot was wafted away by the currents in the aquarium, finding a place at the far end, tucked down behind a large stone. Meanwhile, Redfoot, the crisis over, resumed its composure, with its tiny, soon-to-be-space-occupying clone happily settled beside it. That clone's minuscule tentacles were already sifting the passing water."
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