Black-faced blennies

July 23rd, 2008

Several Black-faced blennies have been found in Dorset and the Nudibranch, Favorinus blianus, was sighted during a dive on Scylla.

The Black-faced blenny, Tripterygion delaisi, is fairly uncommon having been recorded in only three locations on the south coast of Britain. It can reach 9 cm long. Its colouring varies. Both males and females are grey-brown in colour with vertical dark bars. However, in mating season, the males have bright yellow bodies with blue-edged fins and a black head. Males court the females by swimming in a figure of eight.

Photo: Steve Trewhella

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Favorinus blianus reaches 30mm long and has a very pale yellow body. It feeds on the hydroids, Tubularia, and on opisthobranch eggs.

Photo: Douglas Herdson

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Seahorses in Dorset

June 26th, 2008

There have been reports of a number of seahorses sighted during dives in Dorset. The Seahorses are of species Hippocampus hippocampus and Hippocampus guttulatus. Many of the seahorses present were pregnant.

Photo: Steve Trewhella

Hippocampus hippocampus, otherwise known as the short-snouted seahorse can reach about 15cm in length but has a short and fat body shape. It has a short snout, hence its name, that is less than one third of the length of its head. Hippocampus hippocampus has a spine above each eye and bony tubercles on its body that give the seahorse a rather knobbly appearance. Hippocampus hippocampus varies in colour from brown to orange, purple or black and is one of two main species of seahorse found in the UK.

Photo: Steve Trewhella

The long-snouted seahorse, Hippocampus guttulatus, also called the spiny seahorse, grows to about 15cm in length. Like the short-snouted seahorse (Hippocampus hippocampus), it has bony tubercles that give the body a knobbly appearance. This seahorse also has fleshy protuberances on the back of its neck which gives the appearance of a mane. Hippocampus guttulatus is green-yellow to reddish-brown in colour, often with bluish-white spots and flecks.

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The celtic sea slug

May 9th, 2008

The Celtic sea slug (Onchidella celtica) has been sighted on a rocky outcrop at St. Martins Point, Guernsey. Onchidella celtica is a small oval slug with a fleshy body or mantle that is dark green to black in colour and is covered in tubercles. It is about 12mm in length and 6mm in width. When motionless, the mantle covers the head and the foot. The head is only visible when the slug is mobile.

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Sightings of sea hares on Guernsey

April 10th, 2008

There have been a number of sightings of the sea hare Aplysia depilans on Belle Greve Bay, Guernsey from January-April. Aplysia depilans grows to about 30cm long and is brown to green in colour often with pale spots or speckles. As with all species of sea hare, Aplysia depilans has an internal shell and releases ink when disturbed. It is also a herbivore and feeds on seaweeds.

Photo of Aplysia depilans found here.

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Brown venus, fish parasite and jewelbox sighted

March 18th, 2008

Photo: Dave Jarvis

The bivalve Callista chione, also known as the brown venus, was found stranded on a beach in Hayle, Cornwall. Callista chione is an uncommon species in Britain although it is found in South-West England and the Channel Islands. It is a large oval shell that can grow up ton 9cm in length. The outer shell is a reddish-brown colour with darker streaks and the inner shell is an off white colour.

Photo: Steve Trewhella

This isopod, Gnathia maxillaris was also found this month. Gnathia maxillaris is a small isopod; up to 5mm in length and male, female and juvenile Gnathia maxillaris are significantly different in their appearance. The one pictured is a Juvenile. They can usually be found in crevices, empty barnacle shells and Laminaria holdfasts. Around 100 embryos develop inside the body of the female before being released as larvae or Zupheae where they become fish parasites. The usually attach to the bodies of; the Shanny (Lipophrys pholis), the Long-spined Sea Scorpion (Taurulus bubalis) and the Corkwing Wrasse (Symphodus melops). They leave the fish host after a blood meal, their thoracic region expanded and become Pranizae larvae. Not much is known about the adult Gnathia maxillaris but it is believed that they do not feed.

Photo: Steve Trewhella

Found in a fish box in Chesil was the shell Pseudochama gryphina, known as a jewelbox. The first of this species recorded in the UK.

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Sea snail found depositing eggs and boar fish sighted

February 26th, 2008

Lamellaria have been found depositing eggs in Guernsey and Boar fish have been reported in Jersey and Dorset.

On Guernsey’s east coast, Belle Greve Bay, Lamellaria were found excavating holes in ascidians in order to deposit their eggs. Lamellaria has a shell of 10mm length and the animal can grow up to 20mm. This slug-like mollusc varies in colour; yellow, grey or lilac and often with coloured flecks of yellow, black or white. Lamellaria have internal shells enclosed by a mantle which is covered in tubercles. Lamellaria feeds on ascidians and lays their eggs in capsules deposited in holes eaten out of the ascidians by the female. Each flask-like capsule is holds up to 3000 eggs!

In Jersey and Kimmeridge bay, Dorset, Boar fish or Capros aper have been sighted. Capros aper is an oval fish, growing up to 30cm in size. They vary in colour from brick-red for individuals from deep water (200m or more), sometimes with yellow bars, to a yellow-straw coloured fish in shallower waters. It has small, rough scales and feeds on molluscs and crustaceans.

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Discoveries in January

January 22nd, 2008

January brought some unusual, interesting and lesser known species. A Tentacled Lagoon Worm was found in Devon. A Gribble and an interesting parasite were both found on Dorset beaches.

The tentacled lagoon worm (Alkmaria romijni) was found on the Dart estuary in Devon. This is a nationally scarce species. Alkmaria romijni is a small worm, up to 5mm long with eight tentacles which are thread-like and slimy. This species is protected under the Wildlife and Countryside Act 1981 due to it scarcity.

Also found was a gribble (Limnoria lignorum)  boring into wood on a Dorset beach. Gribbles are small wood borers, about 3.5-4mm long.

An interesting find was this whale louse, an ectoparasite found on a dolphin washed up on a beach, again in Dorset.

All Photos: Steve Trewhella

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First UK sighting of snakelocks anemone shrimp

December 2nd, 2007

14 Snakelock Anemone shrimp (Periclimenes sagittifer) were found during a dive off Swanage Pier in Dorset.

Photo: Matt Doggett

Periclimenes sagittifer are small, transparent shrimps which can reach about 3cm in size and usually live symbiotically with the Snakelocks Anemone, giving it its name. This is the first known sighting of Periclimenes sagittifer on mainland Britain.

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Sea hares and thresher sharks

November 22nd, 2007

An uncommon Sea Hare, Aplysia fasciata, has been discovered in September, October and November in the UK. Another unusual and exciting find was a large common Thresher Shark, found in Cornwall.

Aplysia fasciata, rarely seen in the UK, is larger than the common species Aplysia punctata, reaching up to 40cm long (rugby ball sized!) and can weigh up to 2kg! It is usually found on the Atlantic coasts of France, Spain, Portugal and West Africa. Sea hares are large herbivorous sea slugs, feeding on a wide variety of seaweeds. They have a small internal shell and when disturbed, release a cloud of purplish ink. Aplysia fasciata is very dark brown to black in colour. As well as the sea hares themselves, large egg masses, up to 30cm have also been found on the Devon coast.

A skipper, while fishing in the English Channel, south of Land’s end, hauled up a large, female common thresher shark (Alopias vulpinus). It was found to weigh 510 kg (1122 lb) and was 475 cm (15’ 58”) long, although thresher sharks are known to grow to 573 cm (18’8”). Thresher sharks are one of the largest of the approximately 28 sharks found in British water. Thresher sharks have long tails, the same length as their bodies and use these tails to move the fish, usually pilchards, herring and mackerel into tight shoals before attacking. There have been other thresher shark findings recently in Cornwall such as the large shark found in Charlestown which was approximately 400kg (881lb) and 463 cm (15’ 20”) long.

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Jellyfish in November

November 19th, 2007

This month, there have been a number of jellyfish sightings including the String Jellyfish in Cornwall and the Mauve Stinger in the North Channel.

The String Jellyfish Apolemia uvaria, is not actually a jellyfish but belongs to a related group Siphonophora and is related to the Portuguese Man o’ War. They were reported in large numbers and have been spotted off Plymouth sound in the last 4-5 weeks. These unusual creatures have not been recorded in Plymouth or Cornwall before. They are usually found in oceanic waters and have a nasty sting.

Recently, there have been several sightings recorded in the North Channel, North West Ireland and Western Scotland of the jellyfish Pelagia noctiluca, more commonly known as the mauve stinger.

Photo: Steve Trewhella

The mauve stinger can grow up to 10cm in diameter; its tentacles can extend up to 3m and are covered in nematocysts. Its colour varies from mauve-brown to purple and pale red and the exumbrella or the outer surface of the mushroom-shaped bell is covered in nematocyst-bearing warts, pink or mauve in colour. Nematocysts, also called stinging cells, contain small poisoned tubes that deliver its sting. Pelagia noctiluca usually feed on sea squirts and other small jellyfish.

These species also have a nasty sting so approach with care!

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