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However, most of other researchers do not agree that Nectocaris actually being a cephalopod or even mollusk. [140] [141] Early cephalopods were likely predators near the top of the food chain. [25] After the late Cambrian extinction led to the disappearance of many radiodonts, predatory niches became available for other animals. [142]
Other mollusks include gastropods, scaphopods and bivalves. Traditionally, the most common classification of the cephalopods has been a four-fold division (by Bather, 1888), into the orthoceratoids, nautiloids, ammonoids, and coleoids. This article is about nautiloids in that broad sense, sometimes called Nautiloidea sensu lato.
Spirula spirula is a species of deep-water squid-like cephalopod mollusk. It is the only extant member of the genus Spirula , the family Spirulidae , and the order Spirulida . Because of the shape of its internal shell, it is commonly known as the ram's horn squid [ 3 ] or the little post horn squid .
Many species of molluscs are eaten worldwide, either cooked or raw. Some mollusc species are commercially exploited and shipped as part of the international trade in shellfish; other species are harvested, sold and consumed locally. Some species are collected and eaten locally but are rarely bought and sold.
Nautiluses are much closer to the first cephalopods that appeared about 500 million years ago than the early modern cephalopods that appeared maybe 100 million years later (ammonoids and coleoids). They have a seemingly simple brain , not the large complex brains of octopus , cuttlefish and squid , and had long been assumed to lack intelligence.
An ink sac is an anatomical feature that is found in many cephalopod mollusks used to produce the defensive cephalopod ink. With the exception of nocturnal and very deep water cephalopods , all Coleoidea (squid, octopus and cuttlefish) which dwell in light conditions have an ink sac, which can be used to expel a cloud of dark ink in order to ...
Neocoleoidea (most living cephalopods) Coleoidea [ 1 ] [ 2 ] or Dibranchiata is one of the two subclasses of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less" (i.e. octopus , squid and cuttlefish ).
Baculites is an extinct genus of heteromorph ammonite cephalopods with almost straight shells. The genus, which lived worldwide throughout most of the Late Cretaceous, and which briefly survived the K-Pg mass extinction event, was named by Lamarck in 1799. [3] [4]