Rebellious "performance artists" in the sea: The mystery of striped shrimp "standing upside down" is revealed

If ordinary fish are economy class, then striped shrimp are space capsule passengers with VIP customized body parts. Every inch of their body is shouting: "I! Live! To! Stand! Upside! Down!"

Striped shrimpfish, also known as glass fish, razor fish, and blade fish, belongs to the order Acanthopterygii and the family Shrimpfish. It is a tropical nearshore marine fish. Its unique body structure is a model of evolutionary adaptation to the environment. From the overall morphology, its body is extremely flattened and slender like a sharp blade. Its body length is usually no more than 20 cm, like a swimming silver willow leaf. This streamlined body shape not only reduces resistance in the water, but also allows it to flexibly shuttle in the complex environment of coral reefs and seagrass beds. The most eye-catching thing is the stripes on its body: there is a prominent black longitudinal stripe on the side of the body. It blends perfectly with the light and dark shadows of the coral reef to form a natural camouflage barrier, which can not only avoid predators but also facilitate ambush prey.

The snout of the striped shrimpfish extends forward into a slender tubular structure, resembling a delicate straw. This specialized mouth allows it to accurately suck small crustaceans or plankton hiding in crevices. Juvenile individuals are even more peculiar, with a layer of translucent bone plates covering the entire body, as if wearing crystal armor. As they grow, the bone plates of adult fish gradually degenerate, leaving only some protective structures. In addition, their dorsal and anal fins are narrow and positioned backward, and with high-frequency swinging, they can achieve rapid movement over short distances, but their overall swimming speed is slow. They often suspend in an upright posture with their head down and their tail up, and are arranged in a neat "fence array" with group members. From a distance, they look like seaweed swaying with the waves, taking the mimicry survival strategy to the extreme. This all-round adaptation from morphology to behavior makes it an amazing landscape in the coral reef ecosystem.

Striped shrimps are well-known opportunists and often form alliances with long-spined sea urchins. They hide in groups among the venomous spines of sea urchins, using them as mobile fortresses and taking the opportunity to prey on small crustaceans stung by sea urchins. This strategy of "paying protection fees in exchange for safety" can be called the marine version of the "landlord-tenant" relationship.

Striped shrimps are not very good swimmers, and often drift in groups with the current. They will also turn their bodies sideways and swim forward horizontally, but if they feel that they are being targeted by the enemy, they will immediately adjust their posture and stand upside down in the corals for protection. When striped shrimps blend into the corals and seaweed, they can instantly make predators "face-blind". When 20 fish are suspended at a 45-degree angle, the silver stripes + synchronous swaying instantly disguise themselves as a "moving seaweed forest". Scientists have measured that the attack hit rate of the predator wrasse plummeted from 67% to 9% - they were so angry that they almost got glasses for myopia. What's more, they will adjust the group inclination according to the light: when the sun is directly shining at noon, they will collectively "lie flat" to 60 degrees, and at dusk they will straighten up to 30 degrees, just like a group of scheming fish who are proficient in the art of light and shadow.

Next time you see this group of "traitors" while diving, remember to give them a thumbs up for their dancing moves - after all, they are the only ones in the entire ocean who can turn survival into an art and promote human technology at the same time!

Friendly reminder: Please do not imitate this behavior in the swimming pool, otherwise you may be dragged away by the lifeguard as a drowning person. If you really want to try it, it is recommended to sign up for the underwater square dance training class first. The tuition fee is: a bag of shrimp crackers.

References:

[1] Li Xinzheng, Zhang Shiyi. Aquarium Biology[M]. China Forestry Publishing House, 2005.2. Bechert, DW, et al. (2000).