Men are parasites, some might say. But even the most dependent guy around can’t hold a candle to the male anglerfish. Anglers are mostly deep water species found in perpetual blackness. Featured in the movie "Finding Nemo", they are predators that use an antenna-like organ on the forehead to attract smaller fish towards their mouths.
Let’s take a look at this fishing apparatus. This dangling spine is actually a ray of the dorsal fin called an illicium. The illicium hangs in front of the fish’s mouth and terminates in a bait that often resembles the prey of other local fish. This fleshy ending is known as an esca. The esca may look like a worm, a minnow or is filled with biolumenescent bacteria that makes it resemble a small lantern. Whatever the shape, the esca is basically used to attract prey towards the mouth. When another fish is close enough the esca is drawn towards the head of the angler and then the mouth snaps open, drawing the food into the tooth-filled maw. The needle-like teeth point inwards and anything unfortunate enough to be drawn in has no chance of escaping.
Having recently been dumped by the best woman ever, I couldn’t help but wonder how other lesser species of vertebrates manage to catch and hold on to their mates (which may explain my failure at keeping women, I guess). The male anglerfish has done a better job than I’ve done, although I don’t think I’d like to trade places with it.
Living in the depths of the sea, where all light has long since been absorbed by the water, prey isn’t the only thing that animals have trouble finding. Males and females also need some way of locating each other. And the deep-sea anglerfish has come up with an ingenious way of staying with his female once she’s been located.
There is a term in biology called sexual dimorphism. This is a common phenomenon throughout the animal kingdom and explains such simple concepts as the difference in weight and height between male and female humans, the cockscomb of a rooster and the mane of a lion. But rarely is it so pronounced as in the anglerfish. You see, here the males are parasites, unable to live on their own for more than a few days. They are born without their own circulatory or digestive system. Within days they need to locate a female or they will die.
How pathetic is this guy?
But the male’s most accute feature is its olfactory sense. Intensely intuned to the pheromones produced by the female, its first hours of life involve a relentless hunt for a mate. Once she’s found the male latches on to the skin with his teeth. Digestive enzymes are released from the mouth that dissolve the skin of the female and cause the flesh of both sexes to melt and meld. The male is now essentially a fully parasitic being. Once the union is formed all of the male’s organs atrophy until it is nothing but a sperm machine. Acting on pheromonic cues from the female, the male releases his gonads at the female’s whim once a year. This will continue annually for their thirty year or more life span. Suddenly I’m not feeling so sad.
No poll today as this week’s topic has already been determined. We’ll see you Friday with an essay on the Blue Whale.
Other diaries in this series can be found here.