The crab-castrating parasite that zombifies its prey

May 30, 2014 by Tommy Leung

Meet Sacculina carcini – a barnacle that makes a living as a real-life body-snatcher of crabs. Unlike most barnacles that are happy to simply stick themselves to a rock and filter food from the water, Sacculina and its kin have evolved to be parasitic, and they are horrifyingly good at it.

The microscopic larva of Sacculina seeks out an unsuspecting crab using specialised sensory organs. It then settles on a part of the crab where its armours is most vulnerable, usually on the membrane at the base of one of the crab's hair (called a setae).

The larvae then transforms itself into a kind of living hypodermic syringe (called a kentrogon). This syringe stabs the base of the crab's hair and injects the next stage of the parasite – a microscopic blob called the vermigon – into the crab's bloodstream. This blob will eventually grow into a parasite that takes over the crab's entire body.

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Tropical wildlife washed-up on Dorset beaches

3:00pm Saturday 19th December 2009
WILD and windy weather has washed up some rare and unusual visitors to Dorset’s beaches.

Tropical crabs, birds blown off course and rare barnacles are among the wildlife reported by Dorset Wildlife Trust after storms and strong south-westerlies.

Six rare types of goose barnacle have reached the coast in recent weeks, including one, Conchoderma virgatum, which trust staff have nicknamed the “pyjama barnacle” because of its stripy skin.

“These animals usually spend their lives in warmer waters, drifting around the oceans of the world, hitching a lift on any floating debris, whether it be mats of seaweed, bird feathers or plastic bottles,” said Julie Hatcher, marine officer.

Very rarely, other oceanic hitch-hikers find their way to the coastline, including a tropical Columbus crab, found by local marine expert Lin Baldock on Ringstead beach.

This is only the second time in 100 years that Columbus crabs have been found here. They hit the headlines in 2006 when around 30 were discovered on the beaches, following extremely stormy conditions.

Among birds driven by the storms was a grey phalarope, a wading bird blown off course as it headed for the southern oceans from its Arctic breeding grounds.

It was seen surfing the waves and picking tiny bugs from the water just below the trust’s Fine Foundation Marine Centre, at Kimmeridge.

Birds including puffins and petrels, that are normally far out to sea at this time of year, have been washed up dead, battered by the wind and waves and unable to feed.

“Now is the time to get out on the beach and search among the strandline,” said Julie. “After such a stormy period you never know what creatures you may turn up, and it may even be something never recorded in Dorset before.

“Take photos and send them to Dorset Wildlife Trust for recording. The more we know about what’s out there, the better we will be able to protect it,” she said.

Send marine sightings to kimmeridge@dorsetwildlifetrust.org.uk or call 01929 481044.

http://www.bournemouthecho.co.uk/news/4805552.Tropical_wildlife_washed_up_on_Dorset_beaches/

(Submitted by Mark North)

Bass Strait barnacle 300 million-year-old king of species

December 30, 2009

A RARE barnacle found only in Bass Strait is the oldest of the species, as well as one of its most unique members, according to researchers who came across the crustacean by a lucky accident.

The tiny ibliform barnacle, which is just 2.5 millimetres long, dates back to the Paleozoic era, about 300 million years ago.

That means the ibliform barnacle pre-dates all other types of barnacles and gives researchers a clue as to how the species evolved.

''Their earliest forms evolved from Bass Strait and the Tasman Sea,'' said John Buckeridge, professor of natural resources engineering at RMIT University.

And unlike most barnacles, which rely on shells and camouflage to protect them from predators, Professor Buckeridge said the cream-coloured barnacle used the toxic substance bromine, collected from sea water, to make itself unpalatable to predators such as carnivorous snails, small fish and crustaceans.

The ibliform, however, has an incomplete shell that does not cover the barnacle's lower, vulnerable areas where the bromine-heavy parts are mostly concentrated.

Professor Buckeridge's research with RMIT research fellow Jessica Reeves, published this month in the journal Integrative Zoology, found up to 7 per cent of some parts of its body is bromine.

''That's a remarkably high percentage,'' Professor Buckeridge said. ''It's much higher than anything else I've ever seen apart from an algae, also found in Bass Strait. It would be more than unpalatable, it would be poisonous.''

He said there was only one other type of barnacle, the deep sea tetrachaelasma found in waters off Madagascar, which had bromine in its body.

''The shells of these ibliform are made of the same stuff as our teeth. It's a primitive feature not found in modern barnacles,'' Professor Buckeridge said.

The ibliform barnacle, which was recognised as a new species in 2006, is so rare that scientists have only six specimens.

It was found by accident after fishermen delivered a coral-like substance to Museum Victoria, not realising there was a barnacle attached.

http://www.theage.com.au/national/bass-strait-barnacle-300-millionyearold-king-of-species-20091229-lisj.html