Evolution

Taxonomy

Kingdom: Animalia Family: Phocoenidae

Phylum: Chordata Genus: Phocoena

Class: Mammalia Species: Phocoena sinus

Order: Cetacea

Evolutionary changes: Believed that they evolved from Burmeister's porpoises that moved up from South America into the Gulf of California due to geological events that began in the middle Miocene era. They have shared ancestral character of classic porpoise shape but with slightly larger flippers, a smaller skull, and a taller tail fin which is also more curved. The taller tail fin (dorsal) is considered an adaptation for living in warm water and being able to tolerate huge fluctuations in temperature. The size of the dorsal fin allows for extra body heat to disperse. They have polydactyly or extra digits in both flippers too. Non-migratory. Non-selective feeders which eat squid, crabs, and bottom dwelling fish. Utilizes echolocation to find food. Despite diminished gene pool, they are healthy and have not suffered from bottleneck effects. New studies proved that they have had very low population sizes for the last 5, 000 years with little variation. (Chehida, et al., 2020)

References:

Itegrated Taxonomic Information System. Phocoena sinus. Retrieved on May 19, 2022 from https://www.itis.gov/serviet/SingleRpt/SingleRpt?search_topic=TSN&search_value=180474#null/

Myers, P. (1999). "Phocoenidae", Animal Diversity Web. Retrieved on May 20, 2022 from https://animaldiversity.org/accounts/Phocoenidae/

Paul, A. (2022). "Phocoena", Animal Diversity Web. Retrieved on May 20, 2022 from https://animaldiversity.org/accounts/Phocoena/