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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]
The lifespan of nautiluses may exceed 20 years, which is exceptionally lengthy for a cephalopod, many of whom live less than three even in captivity and under ideal living conditions. [37] However, nautiluses typically do not reach sexual maturity until they are about 15 years old, limiting their reproductive lifespan to often less than five years.
Unlike other cephalopods, the eyes of Nautilus species lack ocular muscles and instead move via a stalk, which contains both muscle and connective tissue. Additionally, Nautilus eyes lack any lens or cornea and only have an aperture to allow for light.
They include snails, slugs and other gastropods; clams and other bivalves; squids and other cephalopods; and other lesser-known but similarly distinctive subgroups. The majority of species still live in the oceans, from the seashores to the abyssal zone, but some form a significant part of the freshwater fauna and the terrestrial ecosystems.
For cephalopods in general, the hues of the pigment granules are relatively constant within a species, but can vary slightly between species. For example, the common cuttlefish and the opalescent inshore squid ( Doryteuthis opalescens ) have yellow, red, and brown, the European common squid ( Alloteuthis subulata ) has yellow and red, and the ...
The nature of the siphuncle and its position within the shell are important in classifying nautiloids and can help distinguish them from ammonoids. The siphuncle is on the shell periphery in most ammonoids whereas it runs through the center of the chambers in some nautiloids, including living nautiluses.
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.
Life on Our Planet is an American television nature documentary series released on Netflix and produced by Amblin Television and Silverback Films.Executive-produced by Steven Spielberg and narrated by Morgan Freeman, the series focuses on the evolutionary history of complex life on Earth.