Survival in the Seas
A variety of species in the world's oceans, from microscopic organisms to large sharks, survived the mass extinction 65 million years ago. Many organisms living in freshwater lakes and streams were also relatively unharmed--for reasons that aren't clear.
- Benthic Foraminifera: Single-celled organisms called benthic forams live well below the surface, which might have protected them.
- Corals: Although corals are highly susceptible to certain changes in the environment, they survived the mass extinction.
- Ray-finned fishies: This class of fish includes the majority of fish alive today.
- Sharks: A number of shark species perished 65 million years ago. But those that survived have descendants swimming the oceans today.
- Snails: Numerous groups of snails were hard hit, but others survived.
Chambered nautilus model
Mollusks That Made It
While their relatives the ammonites perished 65 million years ago, nautiloids survived. Living nautiloids include the chambered nautilus.
A freshwater fish lived about 110 million years ago in what is now South America. A close relative survived the mass extinction; living relatives include the freshwater bowfin.
Sponges appeared more than 500 million years ago and have survived multiple mass extinction events. A species that lived at the same time as nonavian dinosaurs closely resembles modern sponges.