The background on octopus species
Octopuses are invertebrates that live in the ocean. They have large heads, big eyes and eight long arms covered in suckers. These arms are used to catch prey, maneuver around the bottom of the ocean and to propel itself through the water. There are 300 species of octopus, including the common octopus, mimic octopus, blue-ringed sea octopus and the giant Pacific octopus. These are all shallow-water finless octopus, the most common kind. There are also a handful of species that fall into the deep-water finned octopus category that have large fins on the side of their heads. The fins look like the ears of an elephant earning one of these species the name “the Dumbo octopus” after the Disney character Dumbo. Let’s compare some of these octopuses:
Common octopus: Brownish-green, 1-3 feet long including arms, most common species, lifespan 1-2 years.Mimic octopus: Light tan with dark brown stripes, 2 feet including arms, can “mimic” other animals like hiding six of their legs and making two of their arms look like sea snakes, lifespan 1-2 years.Blue-ringed sea octopus: Yellow with bright blue circles, small 8-10 inches including arms, are extremely poisonous with venom that is 1000 times more powerful than cyanide! Lifespan 1-2 years.Dumbo octopus: Universal tan color with short arms, 1 foot including arms, lives deep in the bottom of the ocean and has fins on the side of its head. Lifespan 3-5 years.Giant Pacific octopus: Reddish-pink, 14-16 feet including arms, the largest octopus with one of the longest lifespans at 3-5 years.
Why do octopuses have such short lifespans?
The leading cause of death in octopuses is natural causes, but not in a way you might expect! When you think of natural causes you may think of an animal dying of old age but octopuses are typically 1-2 years old when they die, so how can this be? Both the male and female octopus only mate once in life and they die shortly after. Males go on to live a few months after mating before they die and females spend weeks diligently watching over the eggs. She even cleans them and keeps detritus off of them, all 100,000+ eggs. She seems to focus solely on making sure her offspring survive because she will stop eating and never leaves the nest. Once the eggs hatch the female octopus dies seemingly from a lack of food, having used up all of her energy to ensure the safety of her babies. The babies hatch looking like tiny versions of their parents and are equipped to live on their own. Researchers have studied what exactly goes on in the female octopus when it dies. They have studied the optic gland in female octopus and found that the secretions from the optic glad send a message to the octopus to inhibit digestion and salivation. Researches have removed the optic glad from female octopus and found that they live significantly longer.
What Octopus Species Lives the Longest?
Giant Pacific octopuses have among the longest lifespans of any octopus species and live for 3 to 5 years. However, scientists recently discovered an octopus species with a remarkable trait that keeps them living longer than even giant Pacific octopuses! A deep sea octopus – Graneledone boreopacifica – has been observed brooding over its eggs for a 53-month period before they hatched. Here’s what’s truly mind-blowing, the females guarding their eggs in this species were not observed eating across the entire 53 month period! Thanks to this long gestation period, Graneledone boreopacifica is the octopus with the longest known lifespan!
Why do female octopuses die shortly after their eggs hatch?
This is still being studied but one theory is that the main evolutionary task of the octopus is to reproduce and once it has done this its “job” is complete. Another theory lies in the speculation that since octopus can be cannibalistic, a trigger mechanism that makes the mother die protects the new babies from being eaten by their mother. Researchers continue to experiment on these intelligent creatures to learn all that they can.
What other animals die soon after mating?
There is a word for this, semelparity, which means “death after first reproduction”. There are several spider species that the female will eat the male after mating, same with the praying mantis. A marsupial, the male kalutas, a small mouse-like animal, dies right after mating, making it one of the few mammals that do. Salmon are known to travel to their spawning grounds where they die soon after reproducing. One common thread in these animals is that although they only reproduce once they have large numbers of offspring in one episode.
What about the lifespan of squids and cuttlefish?
Octopus, squids and cuttlefish are all cephalopods and have similar characteristics. All three are semelparous (meaning they only reproduce once and die soon after reproducing) but are their lifespans similar? Yes, cuttlefish have an average lifespan of 1-2 years and squid have an average lifespan of 3-5 years. Some of the larger squid species can live quite a bit longer, up to 15 years. Nautiluses are another type of cephalopod. They look similar to octopus but live in a shell and have 90 smaller tentacles that do not have suckers. They take 10-15 years to mature and reproduce more than once so are not semelparous. Their average lifespan is 15-20 years.
If octopuses have a short lifespan and only reproduce once are they endangered?
No! Their system is working just fine. Most species of octopuses are not threatened or endangered according to the IUCN. The common octopus is listed as “Least Concern” by the IUCN. Humans are not a big threat to the octopus population as of now, but fishing and harvesting are listed as potential threats. It is important that the fishing industry adhere to regulations to make sure that balance of these amazing creatures is maintained.
