The Octopus, Man... Essays - Octopuses, Octopodidae, Cephalopod

The Octopus, Man... They change color, texture, and body shape... have three hearts... are jet powered... have members in every ocean of the world... have inspired legends and stories since recorded history... are the most intelligent of all invertibrates, yet are related to clams and oysters... have eyes and senses that rival our own... and can make their own smoke screen decoys out of ink. They are Cephalopods - octopi, cuttlefish, squids, etc. - and they are far more fascinating than one might think. Cephalopoda means, head foot, and they certaintly are of an ancient group... they first appeared several million years before the first primitive fish began to swim the oceans, in the late Cambrian era. They were once one of the dominant life forms in the sea, yet today there are only 650 or so living species left. (This may seem like quite a bit, but compare it to the 30,000 living species of bony fish on this planet and it loses its prominence.) Yet in terms of productivity, some scientists feel that cephalopods are still giving fish a run for their money.With so much information on cephalopods available, it becomes neccesarry to narrow down the catagories. Thus, I have determined to zoom in on the order Octopoda as the main focus of this paper, a group on animals which contains, in my opinion, some of the more interesting and intelligent creatues on this planet. Members of the order octopoda have eight arms. Over the corse of evolution, the trend has been a reduction of shell size. Octopi, having no shells at all, have carried this trend the furthest. The suborder ncerrata contains the familiar, unfinned octopuses that humans know the most about. Octopi have evolved mechanisms to protect themselves from predators. Some of the amazing abilities of octopi include their ability to change theircolor, texture, and apparent size; to expel ink; and to modify their environment to suit themselves. Octopi are able to jet water through their siphon by contracting their mantel to provide quick, explosive thrust. They have the intelligence and ability to get into and out of fishermen's crab and fish traps and to get under an undergravel filter plate in an aquarium. They can adapt to new situations and appear to be curious about their surroundings. Octopi can use their bodies as a nets to trap fish. Having very little hard material in their bodies, usually only a beak and a radula, they can squeeze into amazingly small spaces. You would think that the lack of a hard defensive shell would make the octopus an easy meal. However, the above adaptations that Ive mentioned are often used together to effectively evade their predators. An octopus could darken in color, expel a cloud of dark ink, immediately jet away while turning white, and then disappear under a rock, leaving the predator confused and somewhat perturbed at the situation. Although octopi possess beaks and cephalotoxins, and, if they wanted to or felt the need to, could easily hurt or kill any human who dared to enter their territory, they generally do not affect man... but the exception is a beautiful blue-ringed octopus from Australia. Though it is shy and definitely won't viciously attack, it can, if it feels threatened, defend itself by delivering a venom that can kill in minutes... so if you ever happen to find yourself splashing and swimming around the Great Barrier Reef, just make sure to stay on your toes. The life span of octopi is short, varying from six months in the small species to three years in the larger ones. It is believed that the hormone that regulates sexual maturation is also associated with natural death. Another interesting aspect of octopi is their reproduction. It is generally thought that cephalopods are fast growing animals that reproduce once and then die. In Octopus briareus, an impregnated female can store viable spermatophore for as long as one hundred days after fertilization!!! The eggs are generally laid in a protected lair and fanatically guarded by the female. She usually eats very little or not at all during this period and dies shortly after the eggs hatch. It has been observed that even unfertilized females lay eggs, brood,