Easily distinguished by their long rostrums, serrated above and below. These are very common, but easily overlooked tropical and temperate rock-dwelling shrimps. Most are quite small, and many are semi-transparent. To add to their encryption, these shrimps are able to alter their color and markings to match their oft-commensal hosts, mainly anemones and sea cucumbers. 

Periclimenes commensalis One of a few species of "Crinoid Shrimp" found in the tropical Indo-Pacific. To 1.8 cm. in length. N. Sulawesi (Lembeh Strait) pic.

Periclimenes holthuisi Bruce 1969, Holthuis' Cleaner Shrimp. Found in association with numerous types of stinging-celled life (anemones, corals, mushrooms, the upside-down Jellyfish, Cassiopeia...) (best not kept with Clownfishes though) that they should be purchased with. Eat detritus, any foods. Here on a Plerogyra Coral and with eggs on a Euphylliid Coral in Bunaken/Sulawesi/Indonesia, and a Heliofungia Plate Coral off of Queensland, Australia.  Indo-West Pacific; East Africa, Red Sea to South China Sea, Indonesia, New Caledonia. Some with red markings on abdomen as shown below.

Many more P. holthuisi Pix (click on the blue eh?).

Periclimenes imperator Bruce 1967.  Color variable (depending on host)... including Hexabranchus/Spanish Dancer, Sea Cucumbers (Stichopus, Bohadschia, Synapta), Sea Stars (Gomophia)... Indo-West Pacific; Red Sea, East Africa to Indonesia, Australia, Japan.  Below: N. Sulawesi pix, on Cukes. Second row, on T-Bar Nudibranch, on a giant Melibe Nudibranch,

Periclimenes cf. imperator. Indo-West and Central Pacific. To 2 cm. Found on large seastars, nudibranchs and sea cucumbers. N. Sulawesi images.

Periclimenes inornatus Kemp 1922. Transparent body with a light copper stripe down the middle. Small antennal scale. 7-8 spines on rostrum. Indo-West Pacific. East Africa to Indo., to Micronesia. Usually found on giant anemones (Stichodactyla, Heteractis). N. Sulawesi image on Plerogyra.

Periclimenes koroensis Bruce 1977. Small, but with a conspicuous white head, long chelipeds... antennae, abdomen often hidden in hosts tentacles (mushrooms, anemones). Western Pacific; Philippines, Australia, Marshall Islands. To 4 cm. N. Sulawesi pix in a Euphylliid.

Periclimenes longicarpus Red Sea, Arabian Sea endemic. Usually associated with the Bubble Tip Anemone, Entacmaea quadricolor, here on a Bubble Coral, Plerogyra sinuosa and another just off of its anemone (Gyrostoma helianthus) host, resting on an adjacent Xeniid. There are at least 45 species of commensal shrimps of the subfamily Pontiinae in the Red Sea.

Periclimenes magnificus Bruce 1979. Transparent bodies with four white bands that are made up of white and red dots. Chelipeds, antennae white, legs reddish. Reportedly found on Elegance Coral/Catalaphyllia and the anemone Dolfleina armata. In N. Sulawesi, found on mud bottoms, in association with Snake Eel species... shown.

Periclimenes pedersoni Chace 1958, the Caribbean Anemone Shrimp, Pederson's Shrimp. Should always be kept with Anemone hosts. A great cleaner of fishes, but ships poorly.  Here in a Bartholomea anemone and on a sponge in the Bahamas

Here cleaning the trusting mouth of a Graysby in Grand Turks

Periclimenes psamathe. Tropical Indo-Pacific on black corals, gorgonians, hydroids, anemones and corallimorphs. To two cm. N. Sulawesi (Lembeh Strait) image. Clear bodied with red lines on abdomen.

Periclimenes soror Nobili 1904. Similar, but thinner than P. imperator. Color, markings matching host... Blue on Linckia stars... Found on other stars: Culcita, Acanthaster, Choriaster. Indo-trans-Pacific; Red Sea, East Africa to Hawai'i, Sea of Cortez. Fiji, N. Sulawesi pix... on Culcita and Choriaster.

Periclimenes tenuipes. Tropical Indo-West Pacific. Usually found free living (w/o commensal relation) in and amongst coral rubble. To 3.5 cm. in length. Variably red-tipped chelipeds, white line joining eyes. N. Sulawesi (Lembeh Strait) picture.

Periclimenes tosaensis. Often confused with P. holthuisi which it closely resembles. Found on several hosts, most often anemones of the genus Heteractis. Here on a Euphyllia in N. Sulawesi (Lembeh Strait).

Periclimenes venustus Bruce 1990. Easily confused with P. holthuisi (look for large white spot on abdomen on this species). Found on anemones in shallow water (to 5 m.). At right on a Heliofungia in Mabul and N. Sulawesi, Malaysia. Below on a Stichodactyla and Plerogyra in N. Sulawesi. The latter obviously very differently marked... identification based on Debelius' Crustaceans of the World.

The Spotted Cleaner Shrimp, Periclimenes yucantanicus in its host anemone, Condylactis gigantea off of Cozumel. 3/4-1 in. overall. Also found in association with other tropical West Atlantic anemones. Cozumel and aquarium images.

Periclimenes sp. An unidentified species on a crinoid in N. Sulawesi. Poss. color variant of P. amboinensis, cornutus?

Periclimenes sp. 1 Typified by having a large white abdominal hump patch, banded red and white chelipeds, blue and white telson with red margin. N. Sulawesi pic.

Periclimenes sp. 2. Bright white, wide, flat rostrum like P. imperator, white body chelipeds, eyes, banding like P. venustus, white antennae, white abdominal hump spot and telson, with purple highlights on uropods... you got me! N. Sulawesi pic.

Pliopontonia furtiva Bruce 1973. Only species of the subfamily found in association with corallimorphs. Body as shown, with small yellow and white spots, otherwise translucent. Indo-West Pacific; East Africa to Indonesia, Solomon Islands. N. Sulawesi pic.

Pontonides unciger Calman 1939. Body segments and coloration closely match the black/whip corals (Cirripathes) they inhabit. To about 15 mm. in length (yes, small). Indo-Central Pacific; Red Sea to Indonesia, Australia, Japan, Hawai'i. N. Sulawesi pic.

Pontonides or Pliopontonia sp..  This one on a Corallimorpharian. N. Sulawesi pic.

Vir philippinensis Bruce & Svoboda 1984. Often misidentified as a Periclimenes species (including by me!). Transparent body with purple antennae, purple line running down each leg and cheliped... and only found on Plerogyra/Bubble Coral. West Pacific; Japan, Philippines. N. Sulawesi pic.