Within the waters of Hong Kong is hidden a furtive shinobi🔪, ready for an ambush in the ocean. It possesses transverse stripes, ranging from creamy yellow to very dark brown, throughout its body. It is from this zebra-looking appearance🦓 that it got its common name: the Zebra Mantis Shrimp, known by scientists as 𝘓𝘺𝘴𝘪𝘰𝘴𝘲𝘶𝘪𝘭𝘭𝘪𝘯𝘢 𝘮𝘢𝘤𝘶𝘭𝘢𝘵𝘢 (Fabricius, 1793). Among crustaceans, mantis shrimps are not as famous as crabs🦀, lobsters🦞 or other shrimps but nonetheless, over 450 species have been described, with some presenting vivid colors like the Peacock Mantis Shrimp✌🏻. Unlike the Peacock Mantis Shrimp who live a more solitary lifestyle, the Zebra Mantis Shrimp is often found in monogamous pairs👫🏻.
The Mantis shrimp name is deceiving as they are not true shrimp at all🦐. They have a hard, jointed carapace (shell), and a spread tail similar to a small lobster. In a nutshell, Mantis shrimps are stomatopods which are distant relatives of lobsters, crabs, shrimps, pillbugs (Isopoda) which have since colonized many marine, freshwater and even some terrestrial habitats🌊. Zebra mantis shrimp are distributed across the Indo-Pacific region from East Africa to the Galápagos and Hawaiian Islands🏝. They live in tropical and subtropical coral reefs, sand, mud and rubble strewn coast. The oldest known mantis shrimp fossil dates back to 400 million years ago. Such a long period of time! How have they been so successful in terms of survival? All thanks to their incredible “gadgets” – eyes👀and appendages💪🏻.
To that extent, Zebra mantis shrimps have one of the best morphological adaptations in the animal kingdom, with their stalked eyes covered with white spots. Their eyes can move and explore the environment independently of each other. Whenever a prey, like small fish and shrimps, enters the visual field of one of its eyes, it can detect the prey immediately📡. In many ways, their eyes, and thus vision, are very different when compared to that of humans. Where we require two eyes for depth perception, mantis shrimps only need one. They are also able to detect UV light🔅 and circular polarized light that increase visual contrast, facilitating the detection of prey. Finally, they have great sensitivity towards colours in that they possess 12-channel color vision while humans only get 3 channels🔴🟢🔵.
But those high tech eyes are not the only trick that mantis shrimp possess, as another great adaptation🔫 is found on their front appendages (legs) lined with sharp spines. They ambush prey with their spiky appendages without leaving their burrow🏠, appearing suddenly from the dark; a behaviour that makes them particularly difficult to observe and study for biologists. At the beginning of the hunt, they conceal themselves and peeks their eyes above the entrance of the burrow to check on the approach of their prey. Once the prey is close enough, they emerge suddenly and spear it by unfolding its spiky appendages🔪, quickly dragging it into its burrow. When its “knife” stabs the target, they grab it into their burrow just within a second. Because of this, Zebra mantis shrimp belongs to the group of stomatopods known as “spearers”, while peacock mantis shrimp are “smashers” who use their club-like claws🏒 to smash shelled prey like crabs, snails, rock oysters, and other molluscs🦪. The punch could crack the shells of their prey into pieces🥊.
If you are interested in taking a closer look at these powerful sea warriors, don’t hesitate to come and visit our museum.
Text: Phoebe Leung
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