August 2000

The creatures we call Jellyfish are not really fish, if fact they do not fit into any neat biological category. Science divide the entire animal kingdom into roughly 30 groups, called phyla and gelatinous creatures turn up in at least five of them. Most so-called jellyfish are either ctenophores (comb jellies) or cnidarians, the conventional bell-like shape with stinging tentacles, and some are like worms or snails and also some creatures among our kin, the cordates, pass for jellyfish. Most peoples reaction to jellyfish is "Yuck" when they see a gooey mess on the beach, but as divers we have been privileged to see jellyfish in their natural habitat and we are left to wonder how such unlikely material can create such exquisite beauty, for some jellyfish are among the most beautiful creatures in the world. Their movement too, as they pulse gently through the water can leave you spellbound, I once spent most of one dive just watching a small group of jellyfish performing their mesmeric underwater ballet. Feared by swimmer, loathed by fishermen, long unappreciated by biologists, and repellent to most who encounter them washed up on the beach, these gelatinous animals may be the oceans most efficient predators. What makes them so efficient is their ability to rapidly increase in size and spew out huge blooms of new individuals when there is a glut of food, they are not like the predators of the African plains that can only eat so many of the young Wildebeasts when they are born. In a bay in British Colombia where dense schools of herring turn the water milk white with their spawn, a study showed one year that a bloom of crystal jellies wiped out the entire crop of larval herring, and even when they are not decimating the fish directly, they're always there and always eating, so they are eating up the food that would otherwise go to fish. Copepods are their primary food, but copepods are also the primary food of the larval stages of Cod and many other fish. so if we over fish the Cod for instance, will there be more copepods, and if so will there be more jellyfish spewed out to eat them up, and will the cod have a chance to recover, even if we stop fishing for them?

A student at Brighton University experimenting with an Octopus found that it took 21 days for the octopus to learn how to open a screw top jam jar to get at food that it likes, but that time was honed to one minute after a few days. However after a three day break the octopus took 26 minutes. so it had an incredibly impressive short term memory but a very disappointing long term memory.

There was only one reported stranding during July and that was a Common Dolphin carcass at Little Petherick, that brought to a total of 63 cetacean stranding for this year, March being the worst month when there were 29. Of the 63 there were 36 Common dolphins, 12 Porpoises and 10 unidentified dolphins There were also 3 Pilot Whales and 2 Minke Whales. As well as cetaceans there were also ii Seals, 2 Basking Sharks and 2 Leatherback Turtles, as well as numerous Sea Birds. Although the sea has been relatively calm sightings of Basking Sharks are well down on last year. Several were seen very early in the month but only 2 reports have arrived since 14th July and one of 4 seen off Padstow was rammed in the middle by a boat called Free Spirit, on July 26th. The incident was reported to Padstow Harbour Master. A larger pod of over 20 was seen in Port Issac Bay on the 30th July. Another disturbing incident concerning marine creatures occurred on July 26th off Newquay when a small pod of Bottlenose dolphins were heading eastwards off Lusty Glaze and a small boat began to circle them at high speed, this is blatant harassment and totally unacceptable. Sightings of Dolphins are also down on last year The last reports I had were of a pod of 5 Bottlenose in Port Issac Bay on the 30th, and a pod of 6 Bottlenose in Mounts Bay between Longrock and Eastern Green. on the 28th., earlier a small pod joined surfers at Perranporth on the 20th July. An interesting report came in from someone (probably a visitor) phoning the Caradon Coast and Countryside Officer reporting that there was a Penguin in Looe Harbour, not an uncommon occurrence in Cornwall, but of course we call them Guillemots.

Conservation Officer: Raymond Dennis