Ocean reveals we’re not the only species to use tools

One of my sons received an underwater camera with video for Christmas. They’re not expensive, but to make use of them you’d best be somewhere with acceptable sea temperatures.

Dolphins are known to use sponges when foraging for food, but female Australian & Bahamanian dolphins tear off sponges & fit them over their rostrums.

You can, of course, in Ireland, wear a wet suit but the feel of the sea is surely an essential part of the experience. Also, where the sun shines, views underwater will be broader and

longer, and better lit.

I wish I’d started snorkeling as a teenager, but snorkeling hadn’t reached Ireland then. It was being employed by Mediterranean sponge divers 5,000 years ago, using hollow reeds to breathe through.

One saw no ‘frogmen’ on the holiday beaches in Youghal, Tramore, Ballybunion, or Kilkee, where the family spent a few summer weeks, depending on where my father was stationed. I may, once, have seen a Frenchman with a mask and breathing tube, or maybe he was a German.

Recent research is revealing that fish may be a whole lot smarter than is commonly believed, and some species may, arguably, be ‘tool users’.

A tuskfish breaks open shellfish with a stone; an archer fish shoots insects with jets of water; some dolphins use a sponge when foraging.

Meanwhile, tragically for us, the planet and our children, overfishing, its aftermath, or pollution, means many marine species are disappearing.

The tool-using tuskfish is a species of wrasse — the same family as our Ballan Wrasse and exotically coloured “connors” — that swim between Mauritius in the Indian Ocean and Micronesia, north of Papua New Guinea.

I recently read an eye-witness account by respected marine biologist, Giacomo Bernardi, University of California, of a tuskfish breaking open clams by beating them against a selected stone. He is, likely, the first scientist to film a fish demonstrating tool use.

In the video, the fish exhibits not only tool-use but forward planning. It exposes the clam, found half-buried on the ocean floor, not by squirting water to move the mud off it, but by turning away and snapping its gill covers shut to generate a rush of water, as a book generates a puff of air when snapped shut. Clam exposed, it grips it in its mouth and sets off to find a suitable shell-breaker rock.

It tries one: it’s too small. Some 10m away, it finds a rock heavy enough to serve as an anvil. Using carefully-aimed head flicks, it batters the shell against it until it breaks open.

In the next 20 minutes, it harvests and smashes open three more clams. The rock becomes a work-station, and the fish performs physical labour to earn its lunch.

It is sometimes argued that ‘tool use’ must involve using one object to manipulate another (a bow to shoot an arrow) but the rock is certainly a tool used by the fish.

The tropical archer fish turns water into a tool, a deadly projectile. It can pick off an insect perched or flying at speed above the water at a range of up to 3m, and is 100% accurate at 1m. It forms its jaws into a gun-barrel shape, sucks in water and sends it rocketing from the surface to topple its prey into the stream for easy consumption.

This 10cm colourful inhabitant of tropical rivers from India, the Philippines, and Australia, has further surprises.

Its marksman skills do not come pre-installed. Juveniles cannot, at first, hit a moving target, but after many unsuccessful attempts they hit speeding targets with ease.

Furthermore, they learn to direct the jet so that it doesn’t ‘blow’ the prey onto the river bank, but insures it drops on the water. It can fire single-shot sniper fire, or machine-gun
batteries.

The phenomenal Australian and Bahamanian dolphins that tear off conical sponges and fit them over their rostrums (noses) as we might don gloves are almost all female.

Why, is not known, but it is thought they may descend from a single matrilineal line.

The nose-spongers are ‘specialists’: Not all female dolphins scour the dark sea bottom as solitary hunters.

Their prey are fish that live deep in mud mixed with sharp-edged rock and coral shards which would wound the animals’ noses as they probe. They have no swim bladders and are more nutritious than free-swimming species.

Offspring-bearing females profit. Also, when food is scarce these fish, unknown to other dolphins or fishermen, provide sustenance for pregnant or nursing females.

Mothers teach their daughters, and sometimes a son, the sponge-wearing and hunting techniques. This may be evidence of a non-human cultural tradition.

“The sea, the great unifier, is man’s only hope. Now, as never before, the old phrase has a literal meaning: We are all in the same boat,” said Jacques Cousteau.



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