Viviparidae
Bellamya sp., from Australia. In the Viviparidae (so named because they give birth to small young snails rather than laying eggs), males lack a normal penis, but instead use a modified right tentacle, which is stouter and usually shorter than the normal left tentacle.
Glossary
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature