Glossary of Terms

Spiral cleavage – After the zygote divides into blastomeres, the blastomeres divide at oblique angles to the axis of the embryo (Hickman, 2009).

Indirect lifestyle – G. deflectus has a trochophore and veliger larval stage, which means the snail does not develop directly in its environment (Hickman, 2009).

Triploblastic – Has three germ layers (Hickman, 2009).

Coelom – A body cavity derived from the mesoderm (Hickman, 2009).

Torsion – The body twists in such a way that the anus is over the mouth/gills, which can cause fouling problems (Hickman, 2009).

Trochophore larva – A free-swimming larval stage shown in indirect lifestyl(Hickman, 2009).

Veliger larva- A larval stage that uses cilia to move and the shows shell development (Hickman, 2009).

Sinistral – The shell coils in a counterclockwise fashion (dictionary.com).

Haemoglobin – A protein used for the transport of oxygen through the haemolymph (what organisms use instead of blood in open circulatory systems) (Burch, 1988).

Whorl - A turn or coil of the shell (dictionary.com).

Hirsute periostracum – A bristly covering over the outside of the shell to protect against erosion (dictionary.com).

Radula – A scraping device used for feeding (Hickman, 2009).

Pneumostome - The opening of the lung which is located on the head of the body, next to the anus.(Hickman, 2009).

Hermaphrodic – Both sexes are shown in one organism.

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