“Mermaid Purses”: Strange Enough To Be Fiction

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“Look! I found a big piece of seaweed,” shouts the eccentric five year old as she totes her slimy prize in front of her father. “Sweetie, that’s not seaweed,” he cautiously responds back, tip-toeing around her current happiness. “But what if I told you that you actually found a mermaid’s purse…that contains a baby shark.” And, at this point, I can assume that you and the toddler in question are baffled and innately intrigued.

Encased in Collagen
As much as they may look like a bundled, bulging mass of separated kelp, they’re hardly akin to them. After all, kelp isn’t a “weed” like we’re often lead to believe—and taught, for that matter—to believe; they’re actually an amassing of communal protists. The “egg sacks,” if you will, are actually an encasing collagen. However, it’s a nifty and effective camouflage that envelops the developing embryo.

“Did you see my purse?”
Often times, these biological Louis Vuitton’s end-up in the tidal surf of waters where some reproductive skates, rays, and sharks are found. While they’re most abundantly found anchored amongst sea grasses, mermaid purses are more likely to be cast aside in a rough surf, hidden away in the debris of low-tide that populate always syphoning tidal pools.

Just What’s In That Egg Sack?
Various species of oviparous (developing inside a yolk sack) skates, and chimaeras—more on them in a bit—are known to produce these fertilized egg cases. So, when you look at one of these “mermaid purses”, you’re essentially looking at an eggshell that housed a baby shark.

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“We Can’t Really Put Them In A Box”
Chimaeras (fish belonging to the order of Chimaeriformes) are, essentially, living fossils; they’re likely to be the oldest, aloof fish in existence today. Chimeras closely resemble their “Jaws” ilk, possessing well-pronounced dorsal and pectoral fins. It’s predicted that their body shape and style hasn’t changed much, if at all, over the many, many years these guys have been around.

The saying goes, “if it ain’t broke, don’t fix it”—and the same saying goes for morphology. From the get-go, chimaera were perfectly adapted to their deep-sea niche, extending well beyond eight-thousand feet below the surface. Because of these pressure-hugging depths, the animal’s fertile egg cases are uniquely…well, unique. The collaged-woven casings are atypical amongst the other cartilaginous fish, completely oval in shape and finned around all sides; the design is to help them anchor-down on a leveled ocean floor.