Despite their creepy claws and bright yellow eyes , vampire crabs are increasingly popular pets . Now , experts have discovered two new species of the spooky crustaceans - Geosesarma dennerle and Geosesarma hagen - have been lurking in home aquariums for years . They traced the freshwater crabs ' origins back to their wild source - finding that they live in rivers on the island of Java , Indonesia . Scientists have discovered two new species of the spooky crustaceans - Geosesarma dennerle ( pictured ) and Geosesarma hagen - which are found in many home aquariums . 'These crabs are kind of special because they 've been around in the pet trade for ten years , but no one knew where they come from , ' said Christian Lukhaup , a professional aquarist in Waiblingen , Germany , who was speaking to National Geographic . While scientists have identified a number of vampire crab species before – so called because of their yellow eyes and sometimes purple bodies – the two new species are the most common pets . They may appeal because of their diminutive size , measuring just one inch ( 3cm ) across . While scientists have identified a number of vampire crab species before – so called because of their yellow eyes and sometimes purple bodies – but the two new species are the most common pets . G. hagen is shown . G. dennerle is purple in colour with a cream patch on its back , while G. hagen has a bright orange shell and claws which stand out against the rest of its dark body , according to the study published in the Raffles Bulletin of Zoology . Vampire crabs are so-called because of their spooky yellow eyes , which are the same colour as fictional vampires ' who drink the blood of animals/ . Before being identified as new species , the two types of crabs were known to have originally come from somewhere in Southeast Asia . A site selling vampire crabs says they thrive in aquariums with rocks to climb on and like to sit on Java moss . Females dig down into sand to have their offspring and both sexes are more active in warmer water - typically between 21°C and 27°C ( 70°F and 80°F ) . They are apparently easy to care for and are quite sociable , getting along well with one another and seldom fight . The crabs grow up to one inch wide ( 3cm ) and live for up to three years . Christoph Schubart , co-author of the study from Resenburg University , Germany , said dealers look for bright specimens in areas which may not have been explored by scientists . 'Suddenly the market is formed with some animals that no one has ever given a name , ' he said . Lukhaup , who is from Transylvania , the fabled home of Dracula , used contacts in the aquarium trade to find out where dealers were getting the colourful crabs from and after several false leads , found they come from central Java . He suspects there are more vampire crab species to be uncovered on Indonesia 's islands , because the crabs tend to stay put , meaning different species could exist in different places . However , while this may be exciting for scientists , there are concerns that wild populations could dwindle if too many crabs are collected for pets . They sell for around $ 25 ( £17 ) each . It 's hoped that commercial breeding could prevent this problem . The crabs are amphibious , which Lukhaup thinks may explain why they are brightly coloured- because visual cues are important for communicating on land , while chemical cues reign supreme underwater . Christoph Schubart , co-author of the study from Resenburg University , Germany , said dealers look for bright specimens in areas which may not have been explored by scientists . This image shows the bright purple colouring of G. dennerle , which has striking yellow eyes like some fictional vampires - hence its nickname .
Geosesarma dennerle and Geosesarma hagen are popularly sold as pets . German researchers say they are both new species and come from Java . Traced crustaceans ' origins by talking to dealers of the colourful crabs . Experts think more new species of Vampire crabs are still to be discovered .