Holiday fishes — and jellies

Christmas fish ornamentEvery Christmas season, Minnesota zoo volunteers design, craft and sell an animal ornament as a fundraiser, available for purchase at the zoo’s Minnesota Lodge desk and the penguin booth. Hanging on my tree right now are a flat wooden penguin, crocodile, snowy owl, ring-tailed lemur and seahorse from previous seasons. This year’s addition: a rounded white and yellow fish, casually described by some as a puffer. I haven’t tracked down anyone from the committee that makes these ornaments happen, but to me, the yellow squareness makes it look more like more like a boxfish such as the longhorned cowfish, my latest favorite in Discovery Bay. **

puffer fish

cowfish side view

Animal World points out that puffers (that’s our Tropical Reef puffer directly to the left) and boxfish are closely related, so I’m probably splitting hairs here. The website says the cowfish, Lactoria cornutus (that’s our D-Bay cowfish at lower left), has been getting quite popular: They’ll eat just about anything, and they look rather hilarious. With squared-off edges, a pouty mouth and pointy horns, they swim with a motion that alternates scooting with hovering, unlike the shimmying glide of most fish. The caudal (tail) fin is a collapsible fan — compressed into a stick until they want to execute a turn.

cowfish with jellycowfish tail fanThis website has more to say about cowfish locomotion, their comical looks and their (lack of) suitability for home aquariums, despite their increasing popularity. They’re not a good species to mingle with lots of faster-moving fish, partly because they release toxins when stressed, and their flesh is poisonous. In D-Bay, their primary tankmates don’t move much at all. You can see one such cohabitant clinging to the wall above — an upside-down jellyfish (or as purists call them, jellies, since they’re technically not fish).

upside-down jellyfish close-upIn the wild, and often in their D-Bay tank, these jellies (rarely more than 2 inches in diameter) rest with their bell (or head) on the sandy bottom, legs pointing upward to catch plankton and absorb light, which feeds the algae inside them. As aquarist Becky noted ruefully at a recent volunteer update, the jellies were supposed to be this small aquarium’s chief draw, until the cowfish took center stage. Still, once we remember to look for them, these translucent jellies should remind us that motionless, faceless life forms hold their own intrigue.

**Update!! As of today (Jan. 3), this D-Bay tank has neither cowfish nor jellies, since the former began eating the latter. Fortunately, we have more jellies waiting to be deployed into the tank, and after a quarantine period the cowfish will relocate into the Tropical Reef tank.

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