At the moment–June 22 to July 22—we are in the zodiac sign of Cancer. The sign is called Cancer from the Greek word for crab. Cancer constellation represents the giant crab that attacked Hercules during the second of his twelve labours. It was sent by the goddess Hera to distract Hercules as he battled the water serpent Hydra. Hercules ended up killing the giant crab with his club. In the skies, the crab constellation is a medium-sized one which has ten suns with their own planets.
Down on earth, crabs are members of the animal group called crustaceans—creatures which mostly live in water, have a hard shell, a segmented body, and jointed appendages. Lobsters, shrimps, barnacles are also members of this group. Crabs have five pairs of legs. The first pair has large pinching claws that help with feeding and defence. Three pairs help the crab walk, and last pair may be broad and flattened to serve as paddles for crabs that swim. Though crabs can walk forwards, they generally walk sideways. This is because they have stiff, jointed legs, and find it easier and faster to walk sideways.
There are at least 7,000 species of crab, and they can be found in all oceans and in fresh water. Some crabs even live on land, often several miles from water. They come in a great range of sizes from tiny pea crabs measuring about 2.5 centimeters across, to the giant crab of Japan which may span over 30 centimeters across and measure 4 meters from tip to tip of its stretched out legs.
Some types, including the blue crab, the Dungeness crab, and the king crab, are often eaten by humans. But apart from their nutritional value to humans, and economic value as a major industry, they play a key role in the ecosystem. They are vital food sources for sea animals. The smaller ones recycle nutrients as filter feeders, and the larger ones serve as food for large aquatic mammals. Terrestrial crustaceans are important because they are decomposers of dead organisms. Small crustaceans eat substantial amounts of algae keeping the plant in check, which helps keep the water clear and ensures that sea-grass beds can access to light and oxygen.

India has about 125 species of crabs. The Western Ghats alone, a biodiversity hotspot, is home to 75 species. A new species was discovered here as recently as 2022.
Belonging to Ghatiana genus of fresh water crabs, the new species is called ‘Ghatiana dvivarna’, the name being a combination of the Sanskrit words dvi (two) and varna (colour). The crab is a beautiful white and red-violet.
All this information is very important. But surely there could be more interesting ways to present it?
That is what the Crab Museum in Margate UK tries to do! This museum’s objective is ‘to roll science, humour and philosophy into a unique and satisfyingly baffling day out’! The founders of the museum believe that ‘“’everyone learns better when they’re laughing’”’, and take a goofy approach to their displays. And it seems to be working! The Museum saw over 80,000 visitors last year, and parents report that their children are more engaged here than in many other conventional institutions.
The dioramas, exhibits, text-labels are all planned with humour in mind, even as they are informing the viewers about crab anatomy, mating habits and the importance of these creatures to marine ecosystems. But the Museum goes further—it uses crabs as an entry point to discussing bigger issues, including environmental issues, climate change, capitalism and colonialism.
Other museums are taking note of these unconventional approaches. As reported in the New York Times, ‘Chris Stringer, of the Natural History Museum in London, said in an email that the museum’s silly approach leads to learning “by stealth.” It “teaches more in a small space and short time than many others with far larger budgets.’
We may not be able to visit the Crab Museum at Margate but crab-lovers can participate in their annual Crab Joke Competition. Last year, there were 700 entries, so the competition is quite stiff. One of the top shortlists was:
Why did the crab get bad grades? Because it was below C level!
Jokes apart, we must be aware that various environmental dangers beset crabs. Research says about one-sixth of all freshwater crab species have an elevated risk of extinction, and there are any number of ‘threats to marine species, including illegal and unsustainable fishing, pollution, climate change and disease’.
So in this month of Cancer, let’s spare a thought for crabs and their well-being.
–Meena
Pic acknowledgement: TOI








