Greater amberjack

December 10th, 2009

Seriola dumerili, commonly known as the greater amberjack was sighted in Guernsey. This is the first recording of this fish in Guernsey and it is uncommon to Britain. Seriola dumerili are blue or greenish in adults with a silvery white belly and sides. Sometimes, they have a brown or pinkish tinge. The juveniles are between 2 and 17 cm in length and have five dark body bars which split vertically across their body. The maximum recorded size for Seriola dumerili is 188 cm in length although it is common for them to grow up to 110 cm. The greater Amberjack is carnivorous and feed on other fishes and some invertebrates.

Photo of Seriola dumerili here

The goose barnacle, Conchoderma virgatum was also sighted.

Photo: Steve Trewhella

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Six species of barnacle found in Chesil

November 29th, 2009

Six species of barnacle were found in a week of sightings at Chesil. The six species included; the buoy barnacle Dosima faciculalaria, Scalpellum scalpellum and four species of goose barnacle; Lepas anserifera, Lepas hilli, Lepas pectinata and Lepas anatifera.

Dosima fascicularis is also known as the buoy barnacle. Young forms of the buoy barnacle settle on small floating objects in the water such as twigs or feathers, often in groups of about 2-5 juveniles. As they grow, attached to these objects, they produce a white, spongy secretion from cement glands that acts as a float and is similar in texture to polystyrene. Other barnacles can attach to this float and the colony increases in size. Dosima fascicularis is a pedunculate barnacle (has a stalk) which can be pale yellow to purple-brown in colour. Its capitulum can grow up to 30 mm in length.

Another stalked barnacle, Scalpellum scalpellum, attaches to rocks, hydroids, bryozoans etc. It has a flexible muscular peduncle that has an armour of calcareous scales. Its capitulum grows to about 30 mm in height and is usually a white-grey colour with thirteen plates. This is the only shallow water scalpellid barnacle in British waters.

Lepas anatifera is a common goose barnacle. It attaches itself to large floating objects and consists of two parts; the capitulum and the peduncle. The capitulum is about 50mm in length and contains the feeding tentacles and the body of the barnacle. It is oblong in shape and consists of five white plates separated by red-brown or black tissue. The peduncle is a flexible stalk that can grow from 4 up to 85 cm in length! It attaches the barnacle to floating objects.

Lepas pectinata is a small barnacle with a capitulum of only 15 mm. The outer surface or scutum of the barnacle is ridged and it attaches to both small and large objects, such as seaweed. Lepas anserifera is a rare species that is similar to Lepas pectinata but larger with a capitulum up to 40mm long. The barnacle, Lepas hilli is also a rarer species, similar to Lepas anatifera and is distinguished by a paler band between the peduncle and the capitulum.

All photos: Steve Trewhella

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Discoveries in July

July 29th, 2009

Discoveries this month have included a Slipper Lobster on the Isles of Scilly and a White Sea Bream found on Guernsey.

In the Mouls channel between little Innisvouls and Mouls, in the eastern Isles of Scilly, a slipper lobster was caught in a lobster pot at a depth of 14m.

A White Sea Bream (Diplodus sargus) was caught as part of a shoal of visually similar fish. It is the first White Sea Bream to have been caught and reported in Guernsey.

Click for photo of Diplodus sargus

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Marbled rock crab found on Guernsey

April 28th, 2009

A Marbled Rock Crab (Pachygrapsus marmoratus) was found on Guernsey’s west coast. This could be the first record of this species found on Guernsey. Pachygrapsus marmoratus has a shell or carapace of up to 3.6cm in length and is violet-brown to almost black in colour, with a marbled pattern of yellowish brown. The carapace is almost square in shape. The marbled rock crab is very fast moving and therefore difficult to catch.

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Rare sighting of sea bream in UK

January 29th, 2009

An unusual report for the British Isles is the Two-banded Sea Bream which has been sighted off Guernsey’s north coast. The sea bream, Diplodus vulgaris, has an oblong body that can grow to 45 cm although they usually reach 20-25 cm. They are generally grey, brownish or greenish in colour with a broad black band. These fish are carnivores and feed on crustaceans and molluscs.

Click for photo of Diplodus vulgaris

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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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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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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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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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Unusual sightings in July

August 1st, 2007

Despite reduced numbers of sightings this month, perhaps due to the bad weather, there have been some interesting things sighted, including the Dustbin Lid Jellyfish, caught off the Yorkshire coast, a Cuckoo Wrasse sighted in the St Abbs VMCA, a first for the VMCA and a very unusual record for the East coast, and the nationally scarce Glaucus Pimplet anemone, spotted in North Devon.

The dustbin lid jellyfish, Rhizostoma octopus, is usually found on the southern and western coasts of Britain. The jellyfish is solid in appearance and has a dome shaped bell. Its colour varies from a whitish colour to pale shades of green, blue, pink or brown. In mature Rhizostoma octopus, the Gonads (sex organs) for males are blue in colour and reddish-brown in females. Rhizostoma octopus feed on microscopic planktonic organisms and often, the large crustacean Hyperia galba can be found within the body of the jellyfish.

The cuckoo wrasse (Labrus mixtus) is up to 35cm in length for the males and up to 30cm for the females. The functional (older) males are coloured orange-red with a blue striped head and back while non-functional (young) males and females are pink to orange-red with the females having black and white blotches on their lower back.

Glaucus Pimplet (Anthopleura thallia) is a sea anemone that is rare in the UK. The column grows tall, up to 50mm, the anemone varying in colour; green, brown or grey, sometimes with a reddish overcast. The anemone has up to 100 tentacles of moderate length.

The gales in the last week of July also brought in some unusual pelagic species including an unusual form of goose barnacle found in Dorset and North-West Ireland. Has anyone else found anything unusual washed in?

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