Chinmaya IAS Academy – Current Affairs Chinmaya IAS Academy – Current Affairs
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Praying mantids prey on smaller insects and sometimes the odd frog or lizard. Now, it looks like they’ve added fish to their menu too, for naturalists have observed one catching and eating small ornamental fish in a garden in Bengaluru. Guppy-catcher It was on the evening of March 7 last year that naturalist Rajesh Puttaswamaiah’s young son Arya came running to him at his home in Bengaluru, upset that “some spider-like insect” was catching his prized guppies. A curious Puttaswamaiah went to his first-floor terrace garden, where his large earthenware planter doubles as a mini-pond, replete with water lilies, water cabbage and small ornamental fish including guppies, zebrafish and molly fish. What he saw was extremely intriguing: an almost six centimetre-large praying mantid of the species Hierodula tenuidentata was feasting on a freshly-caught guppy. A few hours later, Puttaswamaiah and his son observed the mantid catch yet another guppy. They observed this for four more days: the mantid would appear at around dusk, fish guppies out of the water and promptly eat them. Over five days, it ate nine male guppies out of the 40 fish in the planter. Such fishing or fish-eating behaviour has never been recorded before in praying mantids, and Puttaswamaiah and his team reported it in the Journal of Orthoptera Research recently. “The mantid’s behaviour raises many questions,” says Puttaswamaiah. Adaptations The compound eyes of most mantids are adapted to daylight, but here was one that managed to hunt fast-moving prey – guppies – in very low light. Moreover, the insect was able to overcome the refraction of light in water (when light travels into water, it slows down, thereby changing direction slightly) which makes it difficult for a terrestrial predator to catch an aquatic creature. Puttaswamaiah and his co-authors argue that the repeated predation also suggests that mantids could learn new hunting strategies from experience and different environmental cues. However, while the observation is interesting, it would be safer to say that mantids have excellent vision and are now known to attack moving prey under water according to Divya Uma, a professor at the Azim Premji University who studies insects including mantids. “Mantids attack any moving object of a particular size,” she wrote in an email. “Mantids (and all insects) can learn, remember and modify their behaviour based on experience. A strike towards a moving prey is an innate response.”
