Sunbathing sunfish mellows in Courtmacsherry

Ocean sunfish: Females produce up to 300m eggs at a time.

IN THE sporadic appearances of summer last week, anglers and their boats went to sea, and even the ocean sunfish were basking, writes Donal Hickey

It is thought that these weird fish (so many fish are “weird” that I use the word advisedly) do actually lie flat on the surface to bask.

Normally, these fore-shortened, tail-less fish swim laterally, the dorsal fin of the rounded body pointing skyward, the other toward the depths. But when the sun shines, they often lie on the surface like a very unusual flatfish, presenting themselves to the warming light or to gulls that might do them the favour of picking parasites off their grey and shimmering skin.

They can be a hazard for boats. They grow up to 3.3m in length and, measuring from fin tip to fin tip, are as broad as they are long. They can weigh up to 2,000kg. Specimens of this size are more likely to be found in water temperatures well above 12C. It is thought that the sunbathing may also be a way of “thermally recharging” after dives into the colder depths.

Ocean sunfish are uncommon but certainly not unknown in our waters, where the winter average is 10C on the south coast, and 7C on the north. However, it may be 16C along southwest coasts in August. Some scientists hold that warming seas seduce them north from tropical waters. It may have been the warmer waters that brought a dozing, half-size sunfish drifting into Billy Barrett’s boat in Courtmacsherry Bay earlier this month.

It was an exceptionally sunny day, and he was fishing between the Horse Rock and Coolim cliffs when he spotted something unusual on the surface. A fisherman and angler for 57 years, anything “out of character” on the surface catches his eye. He stopped his engine, and drifted. The current brought the “object” nearer. The current brought a laidback sunfish, 1.5m from fin to fin, toward him until it bumped gently against the side of his boat.

He had met a larger sunfish in almost exactly the same location the year before. Like its predecessor, it hung around, the sunlight catching the rainbow patterns on its back, its belly yellowish white. He was surprised, but not amazed.

During the salmon drift-netting years, sunfish quite regularly turned up in nets in Cork Harbour. If there was amazement, it was on the part of the fish. It lay against the boat hull and looked up at him with one wide eye, probably the first unfeathered two-legged creature it had ever seen. In time, it drifted away, and Billy continued his fishing.

Ocean sunfish, also called mola mola (“mola” is Latin for “millstone”), “moonfish” in various Mediterranean languages, “swimming-head” in German, “head-only fish” in Polish, is weird indeed. Tail-less and globular, it is the largest bony fish in the world.

It lives on jellyfish, of which it consumes prodigious amounts to maintain its enormous bulk. In turn, sharks, killer whales and sea lions consume it, although the latter often, cruelly, only play with it, snapping off the fins and throwing the body around like a football.

Female sunfish produce up to 300m eggs at a time. The fry, like spiny, six-pointed stars, can grow to 60m times their birth-size.

Sunfish lay more eggs and grow proportionately larger than any other vertebrate.

Despite their immense size, they are docile and do not threaten divers. The only hazard is that, in a collision, their weight will damage a boat or they will jump aboard it, which they have been known to do. Mr Barrett’s long experience had taught him that he was in no danger.

However, a holiday boatman might well experience palpitations upon seeing a 1.5m-round globe drifting toward him, fixing him with one unblinking eye.

On further marine matters, a study detailed in the journal Nature reveals that octopuses have 10,000 more genes than humans. This is attributed to unique and novel genes, possibly involved in camouflage processes helping them to survive, that have no counterparts in other creatures.

Octopuses first developed more than 400m years ago — some 230m years before mammals. “They were the first intelligent beings on the planet”, says Sydney Brenner, the Cambridge University Nobel laureate and founding president of the Okinawa Institute of Science, who initiated the octopus-genome project.

Over the years, I have related a number of personal encounters with intelligent octopuses, in these columns. I have no space left to relate the more amusing incidents. Perhaps next week, if some other natural wonder doesn’t steal the show.


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