The "side-neck" turtles (Pleurodira) fold their neck into a lateral S-shape, so when the head is retracted one side is tucked between the shells. This is a relatively small group of mainly pond-dwelling animals found in South America, Africa (including Madagascar), and Australia. Both of the constituent families (Pelomedusidae and Chelidae) occur in South America. The pelomedusids are also found in Africa, Madagascar, and on some islands of the Indian Ocean, while the chelids occur otherwise in Australia and New Guinea.
One of the best-known side-necks is the bizarre-looking matamata (Chelus fimbriatus) of South America, which lies in wait on the bottom of ponds or rivers and until a fish comes near, then suddenly opens its mouth and expands its throat to "suck in" its prey.
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