Frog crab might look like creatures from a storybook, but this fascinating crab is real! With its frog-like shape and colorful shells, it lives buried in sandy ocean floors, waiting to catch prey.
From their habitats to their nocturnal nature, frog crabs have an intriguing role in marine life. Discover the captivating world of frog crabs! Learn about their unique frog-like appearance, sandy homes, and fascinating habits. Explore everything from their diet to their evolutionary significance in this engaging dive into the life of these extraordinary crustaceans.
A quick overview of frog crab
| Common names | Frog crab |
| Scientific name / Family | Raninidae |
| Size | up to 15 cm long |
| Color | Reddish-brown, orange, brown |
| Lifespan | 4 to 6 years |
| Weight | up to 900 grams |
| Habitat type | Saltwater |
| Temperature | 20°C to 30°C (68°F to 86°F) |
| Diet | Carnivore |
| Sleeping nature | Nocturnal |
Habitat and distribution
Frog crabs live mostly on the seabed, burying themselves in the sand for protection and hunting. They can be found in tropical and subtropical waters, thriving in depths of 10 to 100 meters.
These crabs prefer the warm, shallow waters of the Indo-West Pacific, but they are also spotted off the coasts of the Western Atlantic Ocean, including places like Australia, the Philippines, and parts of Africa.
Appearence
Frog crabs (Raninidae) have a round, frog-like body and claws adapted for digging. Their shells are colored red, orange, and brown with ten white spots, and they have a smooth to rough texture. Their abdomens do not curl beneath their bodies. Their bodies are rounded and well-suited for burying themselves in the sand, much like mole crabs.
Interesting facts about frog crabs
There are 46 species of frog crabs, like Bellcarcinus aptiensis, Ranilia muricata and the most popular being Ranina ranina. Most of their activity is recorded during the night, meaning they are nocturnal and hide during the day, burying themselves in the sand.
Are frog crabs edible?
If you are trying to pet frog crabs, you can. However, they are considered edible crabs. They have consumption popularity in countries like the Philippines, Vietnam and Australia.
Reproduction
The size for first maturity is around 7.4 cm for males and 7.2 cm for females. The crab’s spawning season varies by location, with 10-90% egg-carrying females in Japan, 86% in Hawaii, 1-17% in Thailand, over 50% in the Philippines, and 30-80% in Australia and Taiwan.1 Each female produced 20,000-25,000 eggs with an average egg size of 0.62 mm.
Evolutionary significance
Frog crabs have captured the interest of scientists because they’re fascinating little creatures with some remarkable traits. Studying them helps us understand not just their unique adaptations, but also how they fit into the bigger picture of crustacean life and the ecosystems they inhabit. Their story sheds light on the wonders of evolution and the diverse strategies living beings use to thrive in their environments.
In 2014, scientists have discovered a new frog crab species, Bellcarcinus aptiensis, in Colombia, dating back to the Early Cretaceous period (125-113 million years ago). This find challenges the idea that early frog crabs originated in Eurasia, suggesting instead that they might have emerged in equatorial South America. Named after paleontologist Thomas Bell, this discovery highlights Colombia’s role in the evolution of these unique crabs and offers fresh insights into their history.2
What do frog crabs eat?
Frog crabs need sandy environments to hunt; they bury themselves in sandy areas, leaving their eyes and mouthparts exposed to catching small fish. They are omnivores and feed on a variety of prey such as fish (like sardines), crabs, shrimp, clams, rays, hydroids, copepods, and squid.
Read: Learn about another fascinating species the Squareback marsh crab!
