Navigation Links
Venomous sea snakes play heads or tails with their predators
Date:8/5/2009

In a deadly game of heads or tails venomous sea snakes in the Pacific and Indian Oceans deceive their predators into believing they have two heads, claims research published today in Marine Ecology.

The discovery, made by Dr Arne Redsted Rasmussen and Dr Johan Elmberg, showed that Yellow-lipped Sea Kraits (Laticauda colubrina) use skin markings and behaviour patterns to fool predators into thinking their tail is a second head, complete with lethal venom.

There are over 65 species of sea snakes in the tropical waters of the Southern Hemisphere, ranging from Africa to the Gulf of Panama. Most spend their entire lives in the sea, inhabiting shallow water and are active predators, feeding on small fish found around coral reefs. All sea snakes have extremely potent venom which is among the most toxic known in all snake species.

When hunting for food sea snakes probe crevices and coral formations, temporarily forcing them to drop their guard to threats from the surrounding waters and making them highly vulnerable to attack. However, the Yellow-lipped Sea Krait has been found to twist its tail so that the tip corresponds with the dorsal view of the head, which combined with deceptive colouring, gives the illusion of having two heads and two loads of deadly venom.

Apart from the Yellow-lipped Sea Krait the ecology of sea snakes has largely gone understudied, due mainly to their off-shore and nocturnal behaviour. Yet, despite the number of behavioural studies devoted to this species, the discovery of this false-head-behaviour is a hitherto overlooked anti-predator adaptation.

The discovery was made while senior author Arne Redsted Rasmussen was diving off the coast of the Bunaken Island in Indonesia. A large Krait was followed for thirty minutes, swimming between corals and crevices hunting for food. Rasmussen was momentarily distracted by a second snake, but when looking back he was surprised to see the "head" was facing him while the tail probed the coral. Rasmussen's surprise grew when he saw a second head emerge from the coral instead of the expected tail. It was only when the snake swam away that the first head was clearly seen to be a paddling tail.

To build upon this discovery researchers examined 98 Sea Kraits from three major museum collections in Paris, Berlin and Copenhagen while also monitoring the behaviour of wild Sea Kraits in Solomon Islands during the Danish Galathea 3 Expedition. The research confirmed that all snakes of this species had a distinctive colouration pattern, with a bright yellow horseshoe marking on the tip of the head and the tail. The yellow was deeper than the colours on the rest of the body and the black colorations were much longer than the dark bands on the rest of the body, highlighting the similarity between the head and the tail.

The reason for this mixture of behaviour and coloration results from a developed defence strategy needed when the snake is probing for prey. Despite being extremely venomous sea snakes are susceptible to attack from several predators such as sharks, large bony fishes, and even birds.

"The value of such an adaptation is twofold; it may increase the chances of surviving predator attack by exposing a less 'vital' body part, but more importantly it may deter attack in the first place if attackers perceive the tail as the venomous snakes head," said Rasmussen.

Similar defence mechanisms have been discovered in lizards, and some land snakes have developed ingenious camouflage deterrent behaviour strategies, but this defence has never been associated with other lethally venomous predators such as sea snakes.

Traditionally the only evidence of a defence behaviour strategy in sea snakes has been documented in individual cases, when a snake was exposed to and aware of an imminent danger. This research is the first record of a combined false-head-behaviour and false-head-camouflage defence strategy used as instinct when a snake is hunting for food.

"It is intriguing that this discovery is observed in this species, as one of the key differences between the Yellow-lipped Sea Krait and other sea snakes is that they spend almost equal time on land and in the sea," said Rasmussen. "They therefore live in two worlds where two very different rules of survival apply. It remains to be confirmed whether Sea kraits use their sea defence tactic of motioning their tails when on land."


'/>"/>

Contact: Ben Norman
Benorman@wiley.com
44-124-377-0375
Wiley-Blackwell
Source:Eurekalert

Related biology news :

1. Tentacles of venom: New study reveals all octopuses are venomous
2. Snakes and how they helped our big brains evolve
3. Zoologists: Sea snakes seek out freshwater to slake thirst
4. Snakes, salamanders and other creatures thrive in areas with higher deer populations
5. The evolution of aversion: Why even children are fearful of snakes
6. Magnetic snakes control fluids, gravity-defying droplets, and solving a dragonfly mystery
7. Dogs, humans, put heads together to find cure for brain cancer
8. Our brains make their own marijuana: Were all pot heads deep inside
9. Male crickets with bigger heads are better fighters, study reveals, echoing ancient Chinese text
10. CT scans reveal that dinosaurs were airheads
11. United we stand: When cooperation butts heads with competition
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/1/2016)... 1, 2016  Today, the first day of American ... to develop a first of its kind workplace health ... Watson. In the first application of Watson ... IBM ), and Welltok will create a new offering ... cognitive analytics, delivered on Welltok,s health optimization platform. The ...
(Date:1/25/2016)... Pa. , Jan. 25, 2016   Unisys Corporation ... system at John F. Kennedy (JFK) International Airport, New ... Protection (CBP) identify imposters attempting to enter the ... not belong to them. pilot testing of the ... initially at three terminals at JFK during January 2016. --> ...
(Date:1/21/2016)... , January 21, 2016 ... to a new market research report "Emotion Detection and ... Others), Software Tools (Facial Expression, Voice Recognition and ... - Global forecast to 2020", published by MarketsandMarkets, ... expected to reach USD 22.65 Billion by 2020, ...
Breaking Biology News(10 mins):
(Date:2/4/2016)... -- Spherix Incorporated (Nasdaq: SPEX ) -- an intellectual property development ... property, today provided an update on the Company,s cases ... Texas and announcing that those ... Re-examination ("IPR") proceedings that VTech and Uniden filed ... on only certain claims of two of the patents ...
(Date:2/3/2016)... 2016   ViaCyte, Inc ., a leading, ... stem cell-derived islet replacement therapy for the treatment ... announced that ViaCyte and Janssen Biotech, Inc., one ... Johnson, have agreed to consolidate the assets of ... provides ViaCyte with an exclusive license to all ...
(Date:2/3/2016)... , Feb. 3, 2016 New ... more than $1 million for researchers in ... on health-related research that demonstrates exciting potential.   ... of funding for the New Jersey Health Foundation Research ... members at these educational institutions— Princeton University, Rutgers ...
(Date:2/3/2016)... Mass. , Feb. 3, 2016  Silk Therapeutics, Inc., ... financing round. Silk Therapeutics has now raised a total of ... made by the company. The Series A2 round was led ... Massachusetts , with participation from new investors Lear Corporation ... Sheri and Roy P. Disney ; Richard Sackler , ...
Breaking Biology Technology: