'Vampire' sea lampreys heat up for sex

By Ella Davies,  Reporter, BBC Nature

Male sea lampreys heat up special fat deposits during sexual encounters, scientists have found.

The bizarre vertebrates are best known for their blood-sucking mouths filled with teeth and a razor sharp tongue.

Males also have a raised bump of tissue along their back which they rub against females during courtship.

US researchers discovered that this tissue generates heat in the presence of ovulating females, and heats up more for some than others.

The team from the University of Michigan, US, published their results in the Journal of Experimental Biology.

Sea lampreys are parasitic animals found in the North Atlantic Ocean. The jawless vertebrates look similar to eels and adults can measure over 45cm in length.

Researchers first began to investigate the males' bump, referred to as "rope tissue" by biologists, after observing how it was used in courtship dances.

Continued: http://www.bbc.co.uk/nature/23046826

Blood-sucking fish feed on whales

Blood-sucking sea lampreys feed on prey as big as minke whales, according to new research.


Scientists studying whales in Canada have challenged previous theories that lampreys attach to whales purely to "hitch a ride".

Photographs show bloody lesions after lampreys detached from whale hosts, indicating feeding.

Sea lampreys are parasitic fish that feed on others' blood, attaching to the skin with a suction-cup like mouth.

Sea lampreys (Petromyzon marinus) are known to feed on a wide variety of fish using a funnel-like mouth filled with teeth and a razor-like tongue.


In the past lamprey teeth-marks have been identified on whale and porpoise bodies.

Sea lampreys have also been photographed attached to Pacific humpback and North Atlantic right whales.

Based on these rare glimpses, certain scientists theorised that sea lampreys feed on cetaceans, but it was not possible from this evidence to say conclusively that they were drawing blood.

Others in the scientific community argued that P. marinus could merely be using cetaceans for transport, biting into their flesh in order to travel long distances.

However, during studies in the St Lawrence estuary, where the Great Lakes enter the Atlantic Ocean in eastern Canada, researchers resolved the debate.


The long-term study of minke whales in the area provided the first ongoing observations of sea lamprey and whale interaction.


Their findings were published in the Journal of Fish Biology.

"We and others had long had reason to believe that the lampreys were feeding," said Owen Nichols, Director of the Marine Fisheries Initiative at the Provincetown Center for Coastal Studies in Massachusetts, US.

"The high frequency of minke whale observations coupled with their behaviour in the estuary, frequent surfacings with much of their bodies visible, made these observations possible."

Ursula Tscherter was responsible for the fieldwork during which the research team photographed whales before, during and after lamprey attachment.

"Little is known about lamprey fish on cetaceans especially on minke whales," said Ms Tscherter.

"To document the presence of lamprey fish on individually identified minke whales, which use the St Lawrence estuary as a summer feeding ground, helps to put the topic into a broader context."

The images of bloody lesions on the whales provided the first evidence that the parasites fed on cetacean blood.

"To our knowledge these are the first in-situ observations of such behaviour during which one can convincingly state that lampreys attached to whales are rasping through the skin and feeding rather than just 'hanging on for the ride'," explained Mr Nichols.


Sometimes dubbed the "vampire fish", P. marinus was accidentally introduced to North America's Great Lakes in the 1800s.

Like salmon, sea lampreys are "anadromous", meaning they are born in fresh water, migrate to the sea for their adult life and eventually return to freshwater to spawn and die.

Efforts are now being made to better understand the species in order to control the invasive population that threatens native fish species.

http://news.bbc.co.uk/earth/hi/earth_news/newsid_9281000/9281424.stm

By Ella Davies

Earth News reporter
http://www.blogger.com/post-create.g?blogID=4348728589329576621

Prehistoric bloodsucker in Thames

An ancient blood-sucking fish has been found in the Thames by a 13-year-old boy.

The sea lamprey, an eel-like creature with a sucker-shaped mouth surrounded by teeth, predates the dinosaurs.

But they only venture into fresh water to breed if it is very clean, which is why experts said Oscar Bridge's find is significant.

In the 1960s the Thames was so polluted scientists declared it "biologically extinct" after a survey.

Oscar was taking part in a sponsored clear-up of a riverbank near Fulham's Craven Cottage stadium when he made the discovery.

He said: "All of a sudden I saw this thing and thought, 'what's that?'

"I picked it up and it looked like an eel," he said.

"I did get a shock when I saw the mouth."

He added: "I really like animals - especially creepy ones like that."

What Oscar had found proved to be a 15.5in (40cm) long sea lamprey, one of the most ancient creatures on earth.

Like the shark and the crocodile, sea lampreys have barely changed over thousands of millennia.
The parasitic creature attaches its circular mouth to larger creatures before sucking out their insides.

Chris Coode is river programmes manager for Thames21, the charity that organised the clean-up.

He said: "We have only found one or two in the 15 years we have been cleaning up the Thames.
"The fact they are coming back is a really good sign.

"The Thames is now one of the cleanest city rivers in Europe."

He added: "The lamprey was dead, but it is not a bad thing - because they die immediately after spawning."

On Sunday lampreys were found in the River Wear, County Durham.

The fish was once considered a delicacy - and King Henry I, who lived in the 11th Century, was reputed to have died from eating too many.

However, Oscar said: "It absolutely stank - a horrible fishy smell."

http://news.bbc.co.uk/1/hi/england/london/8127483.stm

Rare fish 'proves water quality'

The discovery of a rare blood-sucking fish in the River Wear is proof of high water quality, conservationists said.

Seven adult sea lampreys, which have toothed, funnel-like sucking mouths, have been found in the river near Chester-le-Street, County Durham.

Only three species of lampreys remain in Britain, and they are protected under European law.

The Environment Agency said the creatures only breed in water which is very clean.

So far the agency has identified twelve spawning sites, known as redds.

Fisheries officer Paul Frear said: "We were thrilled to discover lampreys back in the River Wear, as these rare blood-suckers show us that the water quality in the river is very high.

"Lampreys are extremely selective with their spawning sites and will only nest where the water quality is optimal."

Scientists are continuing to search for more lampreys, and anyone who spots one is asked to report the sighting to the Environment Agency.

http://news.bbc.co.uk/1/hi/england/wear/8122999.stm