This is the Cleaner shrimp Lysmata amboinensis.
This shrimp gets its name from his common symbiotic relationships with 'client' fish in which both organisms benefit; the shrimp gain a meal from eating parasites living on large fish and the clients benefit from the removal of parasites.
Or as below, the "client" was one of the marine biologists.....!
Cleaning organisms including shrimp and fish can congregate in one location on a reef in what is called a "cleaning station" which fish will visit when required; cleaning shrimp perform a rocking dance from side to side to signal their services when fish approach.
L.amboinensis has another peculiar characteristic, an unusual sexual maturation, initially born male once mature they become hermaphrodite allowing them to function as both male and female in interactions with another shrimp.
Many, many thanks to Maxine and Sarah of the The Marine Science Center, where i took these photos. I will be writing about their facility soon, but FYI the The Marine Science Center is an aquarium and laboratory facility, centre of excellence of the Harbour school, on Ap lei Chau Island. The centre is focused on education and outreach program, it is equipped with up-to-date touch tank and aquaria and it hosts a great variety of colourful marine organisms! The MSC brings marine science curriculum into the school and provides a meaningful learning experience for students and the community.
During the school year the Centre is open to visitors every month on specific dates. The staff, composed of two marine biologists, will introduce you Hong Kong marine life and its amazing biodiversity.