Millions of Christmas Island red crabs complete their epic migration across the island to breedIt is one of the wonders of the natural world and also one of its most puzzling.
Every year, millions of tiny red crabs make the arduous trek five kilometres to breed on the beaches of Christmas Island.
Now, scientists have discovered the key to their remarkable athletic feat.
According to research from the University of Bristol, hormonal changes give the crabs the energy to carry out this massive trek.
Lucy Turner, a researcher at the University of Bristol, said: ‘During the wet season on the island, in November or December, and prompted by the arrival of the monsoon rains, millions of the crabs undertake an arduous breeding migration from their home on the high rainforest plateau to the ocean to reproduce.
'This is a journey of several kilometres - a long way when you are a relatively small land crab (less than 20cm long).
‘Scientists have long been puzzled by what mechanisms enable the necessary changes to take place in the crabs’ physiology to allow this journey to take place, and how they make such a dramatic switch from hypoactivity to hyperactivity.’
Scientists have discovered that it is a Crustacean Hyperglycaemic Hormone (CHH) that enables the crabs to make the most efficient use of their stored energy in the muscles (glycogen) and its conversion to glucose to fuel the migration.
Professor Webster, an endocrinologist at Bangor University, added: ‘Their migration is extremely energetically demanding, since the crabs must walk several kilometres over a few days.’
Before the migration, the crabs are inactive and only come out of their burrows to feed.
The team found that giving crabs glucose had a very different outcome depending on whether it was the dry or the wet season.
During the dry season, forced activity resulted in a tremendous release of hormone, within two minutes, irrespective of whether glucose had been administered.
However, in the wet season, the glucose completely prevented the release of the exercise-dependent hormone, showing that they were controlled by a negative feedback loop.
Professor Webster said: ‘Glucose levels were clearly regulating hormone release at this time.
'This made sense since it ensures that during migration, glucose is only released from glycogen stores when glucose levels are low, using the crabs’ precious reserves of glycogen, to ensure that they can complete the migration.’
source: dailymail
Posts
