Zoologists published research this week describing the smallest vertebrate, a new genus of miniature fish in a peat bog in Sumatra, Indonesia. The fish, Paedocypris progenetic, is one of two new species of the new genus described by the scientists in the article. One female of the species measured one millimeter smaller then the next smallest vertebrate (at 7.9 millimeters). The fish are transparent (like the zebrafish embryos, or glassfish), live in peat bogs that have a pH of 3.0 (very acidic), and have unique fins ("bizarre grasping fins"). The scientists said they first discovered the fish in 1996. The Indonesian scientists were joined in their research by Zoologists at the the Raffles Museum of Biodiversity Research in Singapore as well as scientists at the the Natural History Museum and the Max Planck Institute.
This find is an example of evolutionary miniaturization, which is especially common in fish and generally includes a more simplified nervous system, skeletal system and body features. The species characterized in this study are unusual in several ways. In particular they have more complex pelvic girdle and indications of unique reproductive features. The fish are in the carp family (Cyprinidae), and of the ray-finned fish order (Cypriniformes). Transparent fish evade predators because they don't cast shadows or reflect light, especially if they stay still. This particular species doesn't swim very much.
Scientists used to think that peat bogs were too acidic to support life, but scientists have recently found there is a wide variety of fauna in peat bogs, including many species of miniature fishes. Unfortunately these peat bogs are dwindling ecosystems due to development and recent forest fires. The authors note:
"Many of the peat swamps we surveyed throughout Southeast Asia no longer exist and their fauna is eradicated. Populations of all the highly endemic and stenotopic miniature fishes of peat swamps have decreased or collapsed or are extirpated."
Acronym Required previously wrote about a small hominin, Homo florensis, that once inhabited the island of Flores in Indonesia.
