Tuna Crab
Pleuroncodes planipes
Credit: Aquarium of the Pacific / Robin Riggs
SPECIES IN DETAIL
Tuna Crab
Pleuroncodes planipes
CONSERVATION STATUS: Safe for Now
CLIMATE CHANGE: Not Applicable
At the Aquarium
You may view these crabs in the Northern Pacific gallery under the lumpsucker tank.
Geographic Distribution
These crabs live at the west coast of Baja through the Gulf of California and in the California Current. During an El Niño event, their distribution can reach as far north as central California.
Habitat
Larva are planktonic; adults vertically migrate from the seafloor off the continental shelf to the sea surface in nearshore waters. They are typically pelagic but can end up on shore from tidal action. The average depth range is 101—310 meters (331—1,017 feet), but they can be found at the surface of the ocean due to El Niño conditions.
Physical Characteristics
These crabs are known for having large eyes, a long serrated rostrum (the long extension of the carapace located between the eyes), and micro hairs covering its legs. They are orange-red in color and use their tails and legs to swim.
Size
A small species, an adult will grow between 7.6—12.7 centimeters (3—5 inches) long with legs and chelicerae extended.
Diet
Tuna crabs are omnivorous with a diet consisting of items such as zooplankton and phytoplankton. In aquaria settings, they have been known to eat fish.
Reproduction
They are gonochoristic which means that they are separate sexes. The males can exhibit courtship rituals either or both tactile and olfactory means. Males release their sperm (indirect sperm transfer) so that the female can fertilize her eggs. She then broods the eggs until they are able to be released as planktonic larvae.
Behavior
Tuna crabs can swim using their tails and legs. They swim backwards through the water column! They tend to stay in deep waters during the day and move to the shallows at night. A researcher found that one-third of the crabs swim upside down; they swim this way by using the surface tension found at the surface of the water.
Adaptation
The use of their tails in their swimming pattern allows for a powerful thrust in the opposite direction. Swimming upside down could allow for less energy expelled while feeding. Swarming would allow for easier reproduction due to the high availability of the opposite sex.
Longevity
They live for about 3 years.
Conservation
Currently, these crabs are not listed on the International Union for the Conservation of Nature (IUCN) red listing. Their numbers are numerous enough to avoid immediate concern.
Special Notes
The tuna crab is an important food source to many animals such as the blue whale, pinnipeds, birds, and fish.
SPECIES IN DETAIL | Print full entry
Tuna Crab
Pleuroncodes planipes
CONSERVATION STATUS: Safe for Now
CLIMATE CHANGE: Not Applicable
You may view these crabs in the Northern Pacific gallery under the lumpsucker tank.
These crabs live at the west coast of Baja through the Gulf of California and in the California Current. During an El Niño event, their distribution can reach as far north as central California.
Larva are planktonic; adults vertically migrate from the seafloor off the continental shelf to the sea surface in nearshore waters. They are typically pelagic but can end up on shore from tidal action. The average depth range is 101—310 meters (331—1,017 feet), but they can be found at the surface of the ocean due to El Niño conditions.
These crabs are known for having large eyes, a long serrated rostrum (the long extension of the carapace located between the eyes), and micro hairs covering its legs. They are orange-red in color and use their tails and legs to swim.
A small species, an adult will grow between 7.6—12.7 centimeters (3—5 inches) long with legs and chelicerae extended.
Tuna crabs are omnivorous with a diet consisting of items such as zooplankton and phytoplankton. In aquaria settings, they have been known to eat fish.
They are gonochoristic which means that they are separate sexes. The males can exhibit courtship rituals either or both tactile and olfactory means. Males release their sperm (indirect sperm transfer) so that the female can fertilize her eggs. She then broods the eggs until they are able to be released as planktonic larvae.
Tuna crabs can swim using their tails and legs. They swim backwards through the water column! They tend to stay in deep waters during the day and move to the shallows at night. A researcher found that one-third of the crabs swim upside down; they swim this way by using the surface tension found at the surface of the water.
The use of their tails in their swimming pattern allows for a powerful thrust in the opposite direction. Swimming upside down could allow for less energy expelled while feeding. Swarming would allow for easier reproduction due to the high availability of the opposite sex.
They live for about 3 years.
Currently, these crabs are not listed on the International Union for the Conservation of Nature (IUCN) red listing. Their numbers are numerous enough to avoid immediate concern.
The tuna crab is an important food source to many animals such as the blue whale, pinnipeds, birds, and fish.