veliger การใช้

• After hatching, eggs develop into veliger larvae which are planktonic.
• The veliger continues to mature forming the prodissoconch II shell.
• Veliger is about 170 ?m long ( 120-278 ?m ).
• The size of the veliger larvae is about 0.15 mm.
• Later they are released into the sea as veliger larvae.
• Veliger in size 600-700 ?m can undergo metamorphosis into a snail.
• The young hatch as crawling post-veliger larv?
• Species that inhabit estuaries sometimes produce veliger larvae.
• They metamorphose after 15 days into shelled veliger larvae, the more usual form.
• The veliger phase occurs within the eggs.
• The animals are consecutive hermaphrodites and the life history probably includes a free veliger stage.
• The torsion of the visceral mass so distinctive of many gastropods occurs during the veliger stage.
• Veliger larvae are hatched from eggs after four months of development from May to early July.
• Fertilisation is external and the eggs hatch into veliger larvae which become part of the zooplankton.
• Fertilized eggs are brooded inside the periwinkle and the veliger larvae are then released and become planktonic.
• When they have developed to the veliger stage, the larvae emerge from the capsule and become planktonic.
• After hatching, the veliger larvae drift as part of the plankton, eventually settling on the seabed.
• In the end stage of veliger development photosensitive eye spots and elongated foot with a byssal gland are formed.
• Unlike the adult, however, the veliger has two ciliated semi-circular structures resembling fins or wings.
• The shell of a bivalve veliger first appears as a single structure along the dorsal surface of the larva.