Squamates are represented by viviparous, ovoviviparous, and oviparous species. This differs from oviparous and viviparous snakes. Aquarists commonly refer to ovoviviparous and viviparous fish as livebearers. Individuals from viviparous and oviparous populations may be hybridised, but with significant embryonic malformation. Development is usually oviparous (egg-laying) but can be ovoviviparous, or viviparous. Aquarists commonly refer to ovoviviparous and viviparous fish as "livebearers". For both oviparous and viviparous caecilians, delayed investment is a common benefit. They will then begin to reproduce by viviparous parthenogenesis, like most aphids. Great Britain has three native breeds of lizard&colon; slowworms, sand lizards and viviparous lizards. The viviparous lizard feeds on invertebrates, mostly small insects and spiders. Ovoviviparous and viviparous animals also use internal fertilisation. This is consistent with the eggshells surrounding the embryos of viviparous reptiles being non-calcified membranes. This is because viviparous lizards thrive in environments where intraspecific competition is low. There is only one land reptile species native to Ireland, the viviparous or common lizard. Finally he deals with embryogenesis in viviparous animals especially hinds and does.