![]() Ocotopoids and vampyromorphans lack shells altogether. Sepioids and teuthiods have reduced inner shells, while An external shell is possessed onlyīy the Nautiloidea. ![]() The movement of water over the ctenidia is controlled by muscularĬontractions of the funnel or mantle wall. Within the mantle cavity, with the exception of Nautilus, which has two pairs All cephalopods have one pair of unciliated ctenidia The mantle cavity serves as an inhalant aperture, whereas the funnel servesĪs the exhalent aperture. Muscles required for contraction of the cavity and respiration. The mantle surrounds the visceral sac and possesses strong Have more than 90 tentacles members of orders Sepioidea and Teuthoidea haveĮight arms and two tentacles and members of orders Ocotopoidea and Vampyromorpha The arms, tentacles,Īnd funnel are all derivatives of the foot. Cephalopods are characterized by a completely merged head andįoot, with a ring of arms and/or tentacles surrounding the head. ![]() Cephalopoda means "head foot" and this group has the most complex brain of any invertebrate. Cephalopods are strictly marine and are found in all of theĬephalopoda is the most morphologically and behaviorally complex class in There are approximately 650 to 700 extant species of cephalopods in two subclassesĪnd five orders. ![]()
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