Crabs & Shrimps at Night - Reef Life of the Andaman - Part 27
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Banded coral shrimps however
seem to enjoy the presence of divers.
The extra light draws in micro-organisms
and the shrimps take advantage,
plucking food from the water.
This large snapper is tended to by a cleaner shrimp while it rests.
...as is this fimbriated moray.
Space is at a premium on the reef,
and this fimbriated moray finds itself sharing its habitat with a variable coral crab.
Crabs hide deep within the reef during the day
and are hardly seen,
but at night they are highly active.
Females carry their eggs under their apron for a few months
while the embryos develop.
This splendid round crab is ready to release her brood
and begins pumping her lower body.
Thousands of tiny larvae are released and drift away in the current.
This crucifix crab tries to appear as large and intimidating as possible
by spreading its claws,
then attempts to escape our attentions, not by swimming,
but by the more conventional sideways shuffle.
Tiny bull crabs crawl around reefs by night
...and often attach themselves to sea fans.
Flat rock crabs hide in crevices in the reef.
Swimming crabs are here too.
They strongly defend their territory against competitors
such as this passing common decorator crab.
This species grows large claws which can dwarf its small carapace.
They decorate themselves with other marine organisms for camouflage and defense.
This one protects itself with stinging hydroids.
The horrid elbow crab becomes completely encrusted with growth.
Many crabs can voluntarily shed a claw during conflict,
but they can regenerate the missing limb when they next molt their shell.
Spider decorator crabs cover themselves
with small pieces of sponge and other organisms,
allowing them to perfectly blend in with the reef.
The sponges continue to grow while on the crab,
thereby gradually increasing the camouflage.
The sponge crab attempts to hide by carrying a large sponge around with its rearmost legs.
When discovered, it can take drastic action to escape!
Hermit crabs adopt a completely different strategy to self-protection.
The crabs themselves don't have a hard carapace like other crustaceans.
Instead the crab uses an empty snail shell to protect its soft abdomen.
The fourth and fifth pairs of legs
are reduced in size and remain inside the shell,
while long eye stalks enable the crab to peer out.
Hermit crabs literally carry their homes around the reef on their backs.
As the crabs grow they look for larger shells to move to
and the crab is not always so expert at judging the size of its home!
This appears to be a territorial dispute between two anemone hermit crabs.
This species carries live sea anemones on it's shell.
The stinging tentacles of the anemones provide additional protection for the crab.
The anemones benefit too;
mobility gives them a wide variety of feeding opportunities.
When the crab upgrades to a larger shell,
it takes the anemones with it.
By day the naked basket star rests...
