A beautiful translucent crustacean. A rare specialist of small temporary ponds.
Fairy Shrimp, a beautiful translucent crustacean, are what some would call a living fossil as similar forms have been found dating back in the fossil records for over 140 million years.
Adults can be up to 3 cm long, but can begin laying eggs at c.1 cm long. Female Fairy Shrimp have an egg sac at the base of the tail behind the ‘legs’. Male Fairy Shrimp have ‘tusks’ protruding from the head – these are used to grasp females during mating.
Fairy Shrimp depend on clean water ponds that annually dry out, along with the sufficient levels of grazing to add the few necessary nutrients needed by their algal food to grow. These conditions are indicative of a traditional pastoral landscapes.
Fairy Shrimp are the archetypal temporary pond species and have quite a unique life cycle. During the hot summer months their eggs lay dormant waiting for autumn rain to fill their temporary ponds. Once it does, they burst forth, quickly growing and breeding before their ponds once more dry out and their short lives come to a close. Fairy Shrimp can hatch within 48 hours of the pond filling and under ideal conditions will begin to breed within 3 weeks. Their eggs are incredibly well adapted to their conditions. Only a proportion of eggs will hatch each time a pond fills with water. Some eggs will remain dormant for many years, in some cases decades. This means that if a pond dries out before the adults have had time to breed all is not lost and the cycle can continue the next time the pond fills.
Distribution and threats
They are currently listed as Vulnerable in the Red Data Book and are fully protected in the UK under schedule 5 of the Wildlife and Countryside Act.
Although its relatives can be found across Europe, Chirocephalus diaphanus is the only member of the Anostraca family found in Britain, where it is now restricted to a few stronghold including the New Forest, the mawn pools of Powys in Wales and Salisbury Plain.
They are principally threatened by habitat loss and degradation due to infilling of ponds, over grazing, nutrient enrichment and scrub encroachment.