- Domain: Eukarya
- Kingdom: Animalia
- Phylum: Mollusca
- Class: Cephalopoda
- Order: Octopoda
- Genus: Octopus
Their closest relatives are cuttlefishes, squids, and chambered nautiluses, which are all of the class Cephalopoda. So far, about 700 species of cephalopods have been discovered (Hanlon & Messenger). Unlike their fellow cephalopods which all have some sort of shell structure either externally (like the shell of a nautilus) or internally (cuttlefish have a cuttlebone that helps with buoyancy, and squid have a long thin pen that supports their bodies), the only hard part of an octopus's body is their beak. This enables them to squeeze into unusually small spaces, as long as the opening is larger than their beak.
(Source: http://www.octopus.com/anatomy/)
To refresh your memory, an octopus has a head, a mantle, and eight arms. The beak, eyes, and complex brain are all located in the head. The mantle holds the octopus's internal organs, such as its digestive tract, kidneys, and three hearts. One heart pumps blood, which is actually blue, throughout the octopus's body. The other two hearts, known as the branchial hearts, pump blood to the gills where they absorb oxygen as water flows into the mantle. This water is then forced out of a tube called the siphon.
Each arm has one or two rows of suckers along its entire length. These suckers are connected to nerves, which enables the octopus to use them to grab and taste food and other objects. A Giant Pacific Octopus (Enteroctopus dofleini), which is the largest octopus in the world, has two rows on each arm and can have about 1,600 suckers total (FactsMonk). That’s a lot of suckers! Octopus arms are muscular hydrostats, which makes them very strong and flexible. This helps them catch and kill large prey, and even perform some of those escape artist tricks they are known for, such as lifting a heavy lid off of their tank. Muscular hydrostats are basically a mass of muscle that act as skeletal support would in another animal. However, instead of a rigid structure that restricts certain kinds of movement, the muscular hydrostats can bend, elongate, shorten, and twist at any part, even at several parts all simultaneously. This is the same structure that makes up a worm's body, an elephant's trunk, and our tongues!
(Source: http://www.wired.com/wiredscience/2009/09/octopuscontrol/)
Speaking of tongues, octopuses have a radula, also known as a rasping tongue, inside their beaks. The radula has tiny little teeth that scrape food into smaller pieces before swallowing. Octopuses eat mainly crabs, crayfish, and mollusks, including other octopuses. Their predators are seals, sharks, dolphins, eels, and humans. Octopuses are a delicacy in many cultures, especially in Japan, Portugal, the Mediterranean, and Hawaii, and are sometimes eaten alive. According to the USDA, octopuses are actually a good source of B3, B12, potassium, phosphorus, and selenium, but we prefer to think of them as friends rather than food!
(Source: http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/IMAGES/squid_radula.gif)
Sadly, octopuses typically don’t live very long lives; on average their life span is only about one to two years. The Giant Pacific Octopus is the longest-lived; males live to approximately 4 years and females to about 3.5. Males die after mating, and females die shortly after their eggs have hatched. Information for how many eggs an octopus lays is extremely varied but from what we have gathered it seems that they can produce a couple thousand to about two hundred thousand. It seems to depend on the species and individual. The female usually hangs her eggs in strings coming down from the ceiling of her little haven or she individually attaches each egg to the substrate, once again, this depends on the species. The female has a tough life caring for her soon to be born babies. She spends her time guarding them from predators and blowing small currents of water over the eggs so that they are able to get enough oxygen. The female octopus also does not hunt at all during the approximate one month period that she takes care of her eggs and may even ingest her own arms for sustenance! When her eggs finally hatch, mom leaves her little haven but she is extremely weak due to not eating, therefore causing her great vulnerability. She dies soon after her eggs hatch anyways but she is more likely to be eaten by a predator since it is unlikely she will be able to defend herself. Octopuses are not social animals in that they don’t have contact with their mother or learn skills from her. Octopus learn on their own and don’t have any influence from parents or siblings. After her little babies hatch out of their eggs, the young larvae spend their beginning stages of life drifting in clouds of plankton at the surface of the ocean. While drifting they are able to feed on copepods, and larval crabs and starfish. They eventually descend back to the bottom, returning to the deep, but only if the babies are lucky enough to survive the treacherous plankton cloud. In this cloud they are very vulnerable to other plankton eaters. As adults, octopuses live on the ocean floor. One thing we thought was pretty neat is how octopuses will sometimes collect random objects like coconuts or crustacean shells that they come across along the seafloor, and make little homes out of them.
(Source: http://www.wired.com/wiredscience/2009/09/octopuscontrol/)Speaking of tongues, octopuses have a radula, also known as a rasping tongue, inside their beaks. The radula has tiny little teeth that scrape food into smaller pieces before swallowing. Octopuses eat mainly crabs, crayfish, and mollusks, including other octopuses. Their predators are seals, sharks, dolphins, eels, and humans. Octopuses are a delicacy in many cultures, especially in Japan, Portugal, the Mediterranean, and Hawaii, and are sometimes eaten alive. According to the USDA, octopuses are actually a good source of B3, B12, potassium, phosphorus, and selenium, but we prefer to think of them as friends rather than food!
(Source: http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/IMAGES/squid_radula.gif)Sadly, octopuses typically don’t live very long lives; on average their life span is only about one to two years. The Giant Pacific Octopus is the longest-lived; males live to approximately 4 years and females to about 3.5. Males die after mating, and females die shortly after their eggs have hatched. Information for how many eggs an octopus lays is extremely varied but from what we have gathered it seems that they can produce a couple thousand to about two hundred thousand. It seems to depend on the species and individual. The female usually hangs her eggs in strings coming down from the ceiling of her little haven or she individually attaches each egg to the substrate, once again, this depends on the species. The female has a tough life caring for her soon to be born babies. She spends her time guarding them from predators and blowing small currents of water over the eggs so that they are able to get enough oxygen. The female octopus also does not hunt at all during the approximate one month period that she takes care of her eggs and may even ingest her own arms for sustenance! When her eggs finally hatch, mom leaves her little haven but she is extremely weak due to not eating, therefore causing her great vulnerability. She dies soon after her eggs hatch anyways but she is more likely to be eaten by a predator since it is unlikely she will be able to defend herself. Octopuses are not social animals in that they don’t have contact with their mother or learn skills from her. Octopus learn on their own and don’t have any influence from parents or siblings. After her little babies hatch out of their eggs, the young larvae spend their beginning stages of life drifting in clouds of plankton at the surface of the ocean. While drifting they are able to feed on copepods, and larval crabs and starfish. They eventually descend back to the bottom, returning to the deep, but only if the babies are lucky enough to survive the treacherous plankton cloud. In this cloud they are very vulnerable to other plankton eaters. As adults, octopuses live on the ocean floor. One thing we thought was pretty neat is how octopuses will sometimes collect random objects like coconuts or crustacean shells that they come across along the seafloor, and make little homes out of them.
Red Octopus
(Source: http://sanctuaries.noaa.gov/pgallery/pgolympic/living/octopus_300.jpg)
You can find octopuses in all the oceans of the world. The Giant Pacific Octopus, which we have here in our aquarium, is found along coastal waters of the North Pacific. Another species found in Monterey Bay is the Red Octopus (Octopus rubescens). Hopkins Marine Station has an adult Red Octopus, which was caught by one of the lab's scientists when he was diving.
However, due to its wild and quirky behavior this little guy can be pretty tough to work with, so we're lucky that the lab also has baby Two-Spot Octopuses (Octopus bimaculoides). The babies, which were collected in Santa Barbara and hatched at Hopkins, are much easier to handle, and are also extremely cute!Two-Spot Octopus
(Source: http://static.howstuffworks.com/gif/octopus-6.jpg)
Research from:
Cephalopod Behaviour, by Roger T. Hanlon & Roger B. Messenger
http://www.octopus.com/anatomy/
http://animals.nationalgeographic.com/animals/invertebrates/common-octopus.html
http://www.bio.unc.edu/faculty/kier/lab/research.html
http://marinebio.org/species.asp?id=403
http://www.factsmonk.com/octopus_facts
http://www.wikipedia.org/
http://www.bio.unc.edu/faculty/kier/lab/research.html
http://marinebio.org/species.asp?id=403
http://www.factsmonk.com/octopus_facts
http://www.wikipedia.org/
Thanks for posting your experiments, as well as this lovely introduction to octopuses. My daughter is doing her first school project (on the octopus), and this post answered a lot of the questions she had identified for her research.
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