CEPHALOPODS - CEPHALOPODA

Cephalopods-info.
- Check the sub-folders for the specimen information files -
Octopuses, cuttlefish, squids and nautiluses are all members of the same group called cephalopods. This name is a combination of the two Greek words, kephalos meaning head and podos which means foot. In other words, those who have their limbs directly attached to their head. There are around 800 species of the family identified up to date, and are widely regarded as the most intelligent of all invertebrates. The greatest diversity is found in the tropical shallow waters between Thailand, Philippines and northern Australia. Cephalopods come in many different shapes and sizes and live in all seas. Some researchers say there are more cephalopods than fish in the seas. They occur from intertidal reef flats to a few kilometers deep, depending the species. Some species live on or close to the bottom (benthic), while others live in mid-water or close to the surface (pelagic). Most of their limbs or tentacles have suckers which are used to hold on prey or others. The size and quantity of tentacles depends on the species. Cephalopods have a very special skin, which contains pigment cells. These cells are expandable by muscular contraction and makes the animals capable to change colour in seconds. This coloration is used for camouflage, alarm displays, mimicry, and communication. Most cephalopods can produce ink, which comes from a special gland in their liver. When threatened, they will make a "smokescreen" by expelling a dark cloud of ink to confuse any potential predator. Most cephalopods rely on vision to detect prey and predators. They can distinguish the brightness, size, shape and position of objects. They exchange gasses with sea water by forcing water trough their gills, and then squirts the water out of the gill cavity trough their muscular tube-like funnel by contracting the body. This funnel can be aimed in different directions allowing them to use this strong water jet for fast propulsion in case of danger. All living cephalopods have a parrot-like beak and a kind of sandpaper tongue, covered with small teeth (radula). This radula is used to scrape or cut food before it goes direction stomach. Most cephalopods mate and spawn only once (semelparous), they lay many small eggs and die afterwards. When a courting male approaches another family member, he will flash his brightest colours, often in rippling displays. If the other cephalopod is a female and receptive, her skin will change colour to become pale, and mating will occur. If the other cephalopod remains brightly coloured, it is taken as a warning. In warmer waters the cephalopod eggs hatch after a few days, while larger eggs from some cold water species need over a year to develop. The young do not pass trough a larval stage, but directly look the same as their parents. They quickly learn how to hunt, using encounters with prey to refine their strategies.
- Check the sub-folders for the specimen information files -