AN ANNOTATED LIST 
OF THE 
Mammals of San Diego County 
California 
By FRANK STEPHENS 
Order Cetacea 
Cetaceans are mammals that are fishlike in form and adapted 
for life in oceans, seas and large rivers. Like all mammals they 
breathe by means of lungs and suckle their young, which are 
born well developed. 
Family BALAENIDA. Whalebone Whales. 
The food is zoophytes, mollusks, crustaceans and small fish. 
When a quantity of these are taken into the mouth the accom- 
panying water is strained out through the fringed “balleen” of 
the upper jaw, the mouth being partially closed. Whales of this 
family have no teeth. 
1. CALIFORNIA GRAY WHALE. Rhachianectes glaucus. 
Formerly common, now infrequent or nearly extinct. Mi 
grate up and down the coast, at times within sight from the land. 
Seen here from November until April. Hunted for their oil, 
which averages about twenty barrels to the whale. The flesh is 
beginning to be utilized for food. 
2. PACIFIC HUMPBACK WHALE. Megaptera versabilis. 
Nearly exterminated. Migrate irregularly. 
3. SULPHUR-BOTTOMED WHALE. Sibbaldius sulfureus. 
The largest species of whale. Swift and difficult to capture. 
Not common. Migrate irregularly. 
4. PACIFIC FINBACK WHALE. Balenoptera velifera. 
Occasional along the coast. 
Family PHYSETERID. Sperm Whales. 
The food is squid, cuttlefish, octopus, etc. Teeth in lower jaw. 
5. SPERM WHALE. Physeter macrocephalus. 
Found in temperate and tropical seas. Now almost exterm- 
inated. 
Family DELPHINIDE. Dolphins, Porpoises, ete. 
The food is fish, squid, cuttlefish, etc. Gregarious and 
voracious. But little is known about the habits of these small 
cetaceans. Usually there are teeth in both jaws. 
