Dykning med Palaemonide rejer

Koh Lantas Marineliv | Palaemonidae

Palaemonid-rejer er små til mellemstore rejer, der sjældent bliver mere end 5 cm, men nogle få arter er store nok til at have en kommerciel værdi. Disse små rejer lever i tusindvis på koralrevene og dykkerstederne omkring Koh Lanta.

Denne familie af rejer har et langt, tandet næb, og de to forreste ben har kløer. Det andet par ben er større og længere end det første par.

Alle arter i ungdomsstadiet og mange arter i voksenstadiet er gennemsigtige eller næsten gennemsigtige, ofte med mørke linjer eller pletter. Store eksemplarer er nogle gange mere uigennemsigtige og kan være mørkere i farven.

Mange Palaemonid-rejer er kommensale, dvs. de lever på eller i en anden værtsorganisme som f.eks. en svamp, koral eller anemone uden at skade værten. Nogle af de mere farverige arter er i stand til at ændre deres farve, så den matcher deres baggrund eller vært.

De Palaemonid-rejer, der lever sammen med en vært, kan ofte udføre rengøringsopgaver både for deres vært og for forbipasserende havdyr, og de annoncerer typisk deres tilstedeværelse ved at vifte med deres lange hvide antenner for at gøre opmærksom på deres tjenester. Disse renserejer er sammen med rensefisk som f.eks. den blåstribede rensefisk (Labroides dimidiatus) en meget vigtig del af et koralrevs økosystem.

3 arter fundet på denne side:

Harlequin Shrimp (Hymenocera picta)
Peacock-Tail Anemone Shrimp (Periclimenes brevicarpalis)
Bubble Coral Shrimp (Vir philippinensis)

Harlequin Shrimp

(Hymenocera picta)

Hymenocera picta @ Koh Haa

Harlequin Shrimp have a white or cream coloured body which is covered with distinctive red, purple and blue spots. This species of shrimp has ten legs, with the first pair being modified with large, flattened claws. The first pair of antennae on the head resemble a flattened leaf which can sense nearby prey using chemical receptors. The eyes are located on stalks.

Harlequin Shrimp are shy animals, usually found in pairs, and prefer to hide during the day and hunt for prey at night. This species feeds on sea urchins and sea stars, particularly the Blue Sea Star (Linckia laevigata). The shrimp may either cut off a section of the sea star arm with their powerful claws and drag it back to their nest to eat, or may work together to turn over a sea star, thus disabling it, and drag the entire animal back to the nest to eat over a period of time, starting at the end of each arm, eating right up to the central disk.

Harlequin Shrimp can grow up to 5 cm, but usually observed slightly smaller than this, often 3 cm - 4 cm. Females are slightly larger than males, and the monogamous pairs are territorial.

Harlequin Shrimp are members of the sub family Hymenoceridae which has only three members in two genus, the Harlequin Shrimp (genus Hymenocera, only one species) and the tiny Tiger Shrimp (genus Phyllognathia, two species).

Peacock-Tail Anemone Shrimp

(Periclimenes brevicarpalis)

Periclimenes brevicarpalis @ Koh Haa

The Peacock-Tail Anemone Shrimp, sometimes known as the Clown Anemone Shrimp has a translucent body and grows to around 4 cm. The body has several prominent white blotches on the back and tail base. The tail has five black-edged orange spots. The long front legs and claws are transparent with purple bars.

Female Peacock-Tail Anemone Shrimp are often larger and more brightly patterned, with more and larger bright white spots than males. The smaller males may be nearly totally transparent except for the black-edged orange spots on the tail.

The Peacock-Tail Anemone Shrimp lives within anemones and can be found in larger anemones, quite often as a pair.

Bubble Coral Shrimp

(Vir philippinensis)

Vir philippinensis @ Koh Haa

The Bubble Coral Shrimp is translucent with thin blue-black lines extending down the legs and the claw arms. This shrimp has a blue tail margin and lives within bubble corals.

The Bubble Coral Shrimp is usually found in slightly deeper water, 15 m +, and rarely seen shallower than 10 m. There are six bubble coral shrimp species in the Vir genus.