Context: Researchers have found that three fish species that live in the Laccadive Sea, off the southwest corner of the Indian coast are using tools.
Species Discovered:
- The Jansen’s wrasse (Thalassoma jansenii)
- The checkerboard wrasse (Halichoeres hortulanus)
- The moon wrasse (Thalassoma lunare)
This is the first documented instance of using tools in the wild.
All three species used live or dead coral structures as anvils to break the hard shells of sea urchins so they could get to the edible bits inside.
Why do fish need tools?
- The Jansen’s, checkerboard, and moon wrasses were using makeshift tools around them to break open urchin tests.
- The sea urchins (Echinostrephus molaris) are an important agent of reef erosion. They dig deep burrows into the structure of a reef, weakening its overall framework. And they are abundant in Kavaratti.
- Few fish were able to prey on the urchin. E. molaris like most sea urchins is covered in an armour of spines. It also has a hard skeleton called a test that protects its internal organs, making it difficult for fish with unspecialised mouth parts to prey on it.
How did the wrasses use tools?
- Upon finding an urchin, a wrasse would skilfully approach it from the side and use its snout to gingerly turn the urchin over with a series of pushes and jabs.
- The underside of the urchin has fewer and softer spines, allowing the wrasse to safely pick it up in its jaws.
- With the prize in its mouth, the wrasse would swim to a nearby hard coral and strike the urchin against it, dusting off the prickly spines.
- Even more strikes would break open the test as well.
- Once the shell was cracked, the wrasse could eat the soft bits inside.
- In this task, the wrasses used the same coral reef as a tool to achieve two different purposes.