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Cephalopod eggs span a large range of sizes, from 1 to 30 mm in diameter. [129] The fertilised ovum initially divides to produce a disc of germinal cells at one pole, with the yolk remaining at the opposite pole. The germinal disc grows to envelop and eventually absorb the yolk, forming the embryo.
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 ).
The giant squid (Architeuthis dux, pictured) was for a long time thought to be the largest extant cephalopod. It is now known that the colossal squid (Mesonychoteuthis hamiltoni) attains an even greater maximum size. The giant squid seen here measured 9.24 m (30.3 ft) in total length and had a mantle length of 1.79 m (5.9 ft).
Cameroceras exhibited a broad range of sizes, and some species were fairly large by extinct cephalopod standards. One species, C. turrisoides from the Boda Limestone of Sweden , [ 2 ] is estimated to have shell around 2 metres (6.6 ft) in length, [ 3 ] while that of C. rowenaense was about 70 centimetres (2.3 ft). [ 1 ]
Interpretations by Engeser (1996–1998) suggests that nautiloids, and indeed cephalopods in general, should be split into two main clades: Palcephalopoda (including all the nautiloids except Orthocerida and Ascocerida) and Neocephalopoda (the rest of the cephalopods). Palcephalopoda is meant to correspond to groups which are closer to living ...
A new snake species, the northern green anaconda, sits on a riverbank in the Amazon's Orinoco basin. “The size of these magnificent creatures was incredible," Fry said in a news release earlier ...
Orthoceras is a genus of extinct nautiloid cephalopod restricted to Middle Ordovician-aged marine limestones of the Baltic States and Sweden. This genus is sometimes called Orthoceratites . Note it is sometimes misspelled as Orthocera , Orthocerus or Orthoceros .
Orthoceratoidea is a major subclass of nautiloid cephalopods.Members of this subclass usually have orthoconic (straight) to slightly cyrtoconic (curved) shells, and central to subcentral siphuncles which may bear internal deposits. [1]