Hydra are freshwater cnidarians with a tubular body and mobile tentacles: a superficial appearance that is very distinct from humans. However, they are of important biological interest because of their ability to regenerate and because they are one of the few animals that apparently escape some characteristic effects of aging. Hydra also contain homologues to human Myc and Max, which influence cancer and stem cell biology. Chapman, Kirkness, Simakov et al. reveal that the genomic sequence of Hydra magnipapillata contains an estimated 20,000 protein-coding genes, surprisingly similar to the number of protein-coding genes estimated in the human genome. Some important genes are conserved from Hydra to humans, including molecules involved in neuronal signaling. There is significant conservation of cell-cell contact proteins, such as cadherins and β-catenin. The conservation of some systems from Hydra to humans suggests that the Hydra may be a simple and valuable model for medically relevant research.

Chapman
JA
,
Kirkness
EF
,
Simakov
O
,
Hampson
SE
,
Mitros
T
,
Weinmaier
T
,
Rattei
T
,
Balasubramanian
PG
,
Borman
J
,
Busam
D
, et al. 
(
2010
).
The dynamic genome of Hydra
.
Nature
464
,
592
596
.