NAUTILUS
DESCRIPTION
It is a marine cephalopod found in sea-water in Indo-Pacific region, in shallow waters and between the coral walls. It belongs to sub-class Nautiloidea.
NAUTILUS.
The shell of Nautilus is external and spirally coiled. Its outer surface has yellow-brown stripes like ZEBRA. Internal layer of shell is shiny like bead. The cavity of shell is divided into many chambers by a septa. The outermost chamber is the largest and called body chamber which encloses the entire body of Nautilus.
Nautilus: (A) Animal with shell, (B) Shell in section.
Centre pore is present in each septa. From these pores emerge a mantle cord called siphuncle. It helps the animal to excrete gas into the empty chambers. It is differentiated into trunk, head is long and conical bearing a mouth, a pair of eyes and about 90 filiform tentacles without suckers.
Nautilus
Trunk is round and bag-like. Ink-gland is absent. Ospharidium is present. It is nocturnal and rests on the sea surface during day.
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