Crustaceans form a very large group which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill, …. The 67,000 described species range in size from 0.1 mm, to the Japanese spider crab with a leg span of up to 3.8 m; and a mass of 20 kg. Like other arthropods, crustaceans have an exoskeleton, which they moult to grow. For UW macro photographers they are interesting because they are literally to be found everywhere and are often very colorful. They are also a challenge because some of them are very shy, hiding in crevasses or coral heads, some of them are almost translucent, some of them are masters of camouflage and almost completely disappear into the background of the habitat they’re living in or on. They are on the menu of lots of sea dwelling creatures (and men) but some of them have made themselves so useful that no fish would ever even consider eating them or they use some fish as allies to protect them from predators.
Cleaner shrimp are one example. It’s a common name for any swimming crustacean that cleans other organisms of parasites. This is a widely cited example of cleaning symbiosis: a relationship in which both parties benefit. The fish benefit by having parasites removed from them, and the shrimp gain the nutritional value of the parasites. In many coral reefs, cleaner shrimp congregate at cleaning stations.
The other example is partner shrimps. They are known for burrowing into sand, mud, and gravel with their front claws. However, they prefer to burrow in lagoons and reef edges - areas with little to no cover from predators. This precarious housing location, combined with their relatively poor eyesight, requires partner shrimp to solicit the help of certain gobies. As the goby uses the shrimp's burrow for protection from predators, it also acts as "eyes" for the shrimp. During the day, the goby hovers above the burrow, feeding and interacting with other gobies. Meanwhile, the shrimp uses its antennae to stay in constant contact with the goby's tail while searching for food (detritus, tiny crustaceans and worms) and maintaining the burrow opening. If a predatory fish approaches, the goby flicks its tail several times, alerting the shrimp to retreat into the burrow. If the predator comes within striking distance, the goby will dart headfirst into the burrow. During the night, the two simply rest together in the burrow.
The red-dotted guard crab is a small coral crab with brown to purple carapace and red/brown claws with brown pincers. On the inside of carpus (the upper section of the claws) it has eight spines. On the upper side of the carapace you can often see rows of fine red spots. Nuweiba, Gulf of Aqaba, Egypt
Mantis shrimps are commonly separated into two distinct groups determined by the manner of claws they possess,the Smashers and the Spearers.are predators.They are aggressive and live typically solitary. Odontodactylus latirostris is a Smasher. Lembeh Strait, North Sulawesi, Indonesia.
Commonly known as the harlequin shrimp. They reach about 5 centimetres (2.0 in) in length, live in pairs and feed exclusively on starfish, including crown-of-thorns starfish. It does seem to prefer smaller, more sedentary starfish, but as these generally are not sufficiently numerous for its needs, it commonly will attack Acanthaster, both reducing its consumption of coral while under attack, and killing it within a few days. Lembeh Strait, North Sulawesi, Indonesia.
Translucent with large white area on carapace and another on abdomen. Red speckles cover legs, eye-stalks, antennae and claw arms. Commensal with corals Heliofungia spp and Goniopora spp. Lembeh Strait, North Sulawesi, Indonesia.
The hairy or algae shrimp (5mm) has a tiny, wispy bent-back profile with its tail pointed up. It is covered with either brown, green or yellow filaments disguising their body shape. Often move about just above bottom resembling floating bits of algae. Lembeh Strait, North Sulawesi, Indonesia.
The squat shrimp is a very common shrimp. They are brown with several large white and brown circular markings, sometimes with a blue line around the circles. They typically hold their tails vertically. Frequently groups associate with anemones, often near the edges of the host. The females are larger than males. Found in Anilao, South Luzon, Philippines.
On my bed of pins... Zebrida adamsii is a distinctively striped species of crab that lives in association with a sea urchin in the Indo-Pacific region. It is cryptically coloured with vertical stripes and has special adaptations to its legs to enable it to cling to its host's spines. Anilao, South Luzon, Philippines
Nice and snug in my tube. The claws of this hermit crab come in shades of red to brown with white patches and white pincer tips. Their white-spotted dark eyes stand on pale stalks with black stripes. They have long feathery antennae. These crabs live in tubes in living coral. Anilao, South Luzon, Philippines.
Pearly eyes. This shrimp has a translucent body with stripes in the same color as its coral host. Its carapace is smoothly rounded. (10mm) Anilao, South Luzon, Philippines.
The peacock mantis shrimp, harlequin mantis shrimp, painted mantis shrimp, or clown mantis shrimp, is a large mantis shrimp. Their ability to see circularly polarized light has led to studies to determine if the mechanisms by which their eyes operate can be replicated for use in reading CDs and similar optical information-storage devices. Lembeh Strait, North Sulawesi, Indonesia
Minuscule crab living on a sea pen. They exist in a ray of different colors. Lembeh Strait, North Sulawesi, Indonesia.
Commonly known as the harlequin shrimp, is a species of saltwater shrimp found at coral reefs in the tropical Indian and Pacific oceans. They reach about 5 centimeters (2.0 in) in length, live in pairs and feed exclusively on starfish, including crown-of-thorns starfish. It commonly will attack crown-of-thorns starfish, both reducing its consumption of coral while under attack, and killing it within a few days. Lembeh Strait, North Sulawesi, Indonesia
The spotted-leg guard crab is white to pink or pale orange carapace; reddish yellow legs with numerous spots; claws with dark wavy line markings. Commensal with branching corals. They use their claws to ward off coral predators. Lembeh Strait, North Sulawesi, Indonesia
ALLOGALATHEA ELEGANS The body of the elegant crinoid squat lobster is droplet-shaped. The first pair of legs are endowed with pincers and are longer than the animal body. The animal's size depends on the sex. Females are usually bigger than males but never grow over 2 cm. The animal's coloration is variable and is matching the colors of its host but not systematically. It can be uniform and varied from dark red, blackish purple, orange or brown. Lembeh Strait, North Sulawesi, Indonesia
Used to be called Periclemenes imperator. The emperor shrimp is typically red with prominent white pattern on head, back and tail. Orange claw arms with purple claws and joints. Commensal with several species of sea cucumbers and larger nudibranchs. They feed on detritus picked off the sea floor. Anilao, South Luzon, Philippines.
Durban hinge-beak shrimp are common and wide spread. White band separating carapace from abdomen, red legs with white stripes. Like most genus member often live in groups. Older males develop long claw arms used in mate guarding and mating. Nuweiba, South Sinaï, Egypt.
The leopard crinoid shrimp is white with irregular lateral banding extending from the flattened antennal scales to the tail. There are blotches and dots in between. Secondary colors match host crinoid. Sabang, Puerto Galera, Mindoro Oriental, Philippines.
This swimming crab is characterised by a brownish upper surface with some white spots among the wafts or bright red granules. On its under surface it is bluish, mottled with white and pale red. This crab is not a major target for commercial fishing. Anilao, South Luzon, Philippines.
Marbled shrimp are almost otherworldly! Color patterns consist mainly of blotches, spots and marbling, usually earth-tone colors. Brushlike cirri on the head, body and appendages may act to break up their outline so that they are less conspicuous to predators. Saron tend to be inactive and may rely on remaining still, as well as camouflage, to go undetected. Likes to lurk in crevices or among coral rubble. Moves into more exposed areas of reefs to feed at night. Nuweiba, South Sinaï, Egypt.
The Magnificent Shrimpgoby living in symbiosis with the red and white coloured Randall’s Alpheid Shrimp. They live at depths from 15 to 40m. This one had his burrow at about 30 m depth. Anilao, South Luzon, Philippines.
The Holthuis anemone shrimp is translucent with prominent white saddle marking encircled in brown on abdominal hump. This partner shrimp has a symbiotic relationship with the anemone, removing dead skin and other unwanted items from its surface while being immune to the tentacles' stinging nematocysts. Sabang, Puerto Galera, Mindoro Oriental, Philippines.
The hairy or algae shrimp (5mm) has a tiny, wispy bent-back profile with its tail pointed up. It is covered with either brown, green or yellow filaments disguising their body shape. Often move about just above bottom resembling floating bits of algae. Anilao, South Luzon, Philippines.
The harlequin swimming crab has large white spots and markings on carapace and bands on claw arms; whitish translucent legs. Usually lives in association with tube-dwelling anemones. Lembeh Strait, North Sulawesi, Indonesia.
Spider squat lobster has a tiny carapace with spider-like long legs, brick red with yellow lines on the carapace and white spots on the upper segment of the legs. Lembeh Strait, North Sulawesi, Indonesia