Most teeth (lifetime)

The animal with the most teeth is the umbrella slug (Umbraculum umbraculum), an Indo-Pacific species of sea snail. It produces approximately 750,000 tiny teeth during its lifetime, which is up to 10 years. Its teeth are constantly replaced as fast as they wear down, but at any one given time it possesses approximately 70–80 rows of teeth on its radula – a broad rasping tongue-like organ – with each row containing around 17–18 teeth (thus totalling almost 1,500) arranged in a V-shape. It uses its radula to scrape and feed upon hard-bodied sponges, as well as bivalve molluscs like clams and mussels.

The umbrella slug is a particular type of small (up to 20 cm/6 in) gastropod sea snail known as a false limpet, on account of its superficially limpet-like conical shell. It occurs widely in the Indo-Pacific's tropical waters, including Indonesia, Mexico, Panama, Hawaii, Australia and New Zealand, as well as in the Atlantic Ocean's warmer waters, and also the Mediterranean Sea and the Red Sea.

The land animal with the most known teeth is the common leaf-tailed gecko Uroplatus fimbriatus of Madagascar. It possesses a total of 169 teeth in its upper jaw and 148 in its lower jaw, making a grand total of 317. Only certain prehistoric pterosaurs (flying reptiles) possessed a greater teeth count than this among non-aquatic animals. Why this gecko has such a bizarrely high number of teeth remains a mystery.