Search results
Results from the WOW.Com Content Network
Cephalopods are thought to be unable to live in fresh water due to multiple biochemical constraints, and in their >400 million year existence have never ventured into fully freshwater habitats. [10] Cephalopods occupy most of the depth of the ocean, from the abyssal plains to the sea surface, and have also been found in the hadal zone. [11]
This serves either as a warning, when they are poisonous or contain stinging cells, or to camouflage them on the brightly colored hydroids, sponges, and seaweeds on which many of the species are found. Lateral outgrowths on the body of nudibranchs are called cerata. These contain an outpocketing of digestive glands called the diverticula.
The cephalopod radula rarely fossilizes: it has been found in around one in five ammonite genera, and is rarer still in non-ammonoid forms. Indeed, it is known from only three non-ammonoid taxa in the Palaeozoic era: Michelinoceras , Paleocadmus , and an unnamed species from the Soom Shale .
The cephalopods have a long geological history, with the first nautiloids found in late Cambrian strata. [1] The class developed during the middle Cambrian, and underwent pulses of diversification during the Ordovician period [2] to become diverse and dominant in the Paleozoic and Mesozoic seas.
Depending on the species and family concerned, some bivalves utilize their inhalant siphon like the hose of a vacuum cleaner, and actively suck up food particles from the marine substrate. Most other bivalves ingest microscopic phytoplankton as food from the general water supply, which enters via the inhalant siphon and reaches the mouth after ...
Hemocyanins are found in the Mollusca and Arthropoda, including cephalopods and crustaceans, and utilized by some land arthropods such as the tarantula Eurypelma californicum, [3] the emperor scorpion, [4] and the centipede Scutigera coleoptrata. Also, larval storage proteins in many insects appear to be derived from hemocyanins.
Unlike other tuna that eat primarily fish, for example the bigeye and yellowfin tuna, the albacore's main source of food is cephalopods. The most abundant cephalopod in its diet is Heteroteuthis dispar, a tiny deep-water squid found in the Mediterranean Sea and Atlantic Ocean. Another cephalopod species preyed upon is Berryteuthis anonychus. [16]
The pelagic food web, showing the central involvement of marine microorganisms in how the ocean imports nutrients from and then exports them back to the atmosphere and ocean floor. A marine food web is a food web of marine life. At the base of the ocean food web are single-celled algae and other plant-like organisms known as phytoplankton.