Whale Shark Wine and Dine

While the announcer’s voice usually annoys me, I found this clip to be particularly interesting. They actually get into a nice little sidebar about the natural history of the fish that produce the eggs whale sharks like to eat. One thing I’ve always wanted to know is, why do they have the pattern of of dots and stripes on their back? Does it have a purpose? Can’t be camoflage, they are one of the biggest fish in the sea.  Any ideas from our shark-savvy readership? What is the closest phylogenetic relative to the whale shark?

6 Replies to “Whale Shark Wine and Dine”

  1. Most elasmobranch phylogenies place whale sharks within Orectolobiformes (carpet sharks), which is a Galeomorph order along with Heterodontiformes (bullhead sharks), Lamniformes (mackerel sharks), and Carcharhiniformes (ground or whaler sharks). The idea of “closest phylogenetic relative” is a bit tricky, as it’s the only one in its family and genus.

    No idea on the spots, although most of the other Orectolobiform species also have them — i.e., it could simply be a relict trait, perhaps?

  2. From the Florida Museum of Natural History:

    Whale sharks are greyish, bluish or brownish above, with an upper surface pattern of creamy white spots between pale, vertical and horizontal stripes. The belly is white. The function of the distinctive pattern of body mark is unknown. Many bottom-dwelling sharks have bold and disruptive body markings that act as camouflage through disruptive coloration. The whale shark’s markings could be a result of its evolutionary relationship with bottom dwelling carpet sharks. Distinctive markings in a pelagic species could be linked to social activities such as postural displays and recognition processes. Another possibility is that these pigment patterns could be an adaptation for radiation shielding, important in a species that may spend a significant proportion of time in surface waters possibly exposed to high levels of ultraviolet radiation.

    Juvenile whale sharks have this pattern too, and maybe it helps them avoid predation. There is a lot of research going on with these animal in Central America, where the locals refer to them as the domino fish.

  3. Oh yeah, and one last thing, the pattern is unique for each animal so researchers can use the spots to identify individuals. Rachel Graham was one of the first researchers to document the whale sharks feeding on snapper spawn off the coast of Belize.

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