EPOW - Ecology Picture of the Week

Extinct volcanic cone, Isla El Muerto
Sea of Cortez, Baja California, Mexico

Explanation:  Once upon a time, I was part of a diving expedition to some islands in the Sea of Cortez off Baja California.  After several days pounding along sand and dirt-rutted roads, someplace south of San Felipe we put in and were boated to this stark island, after which the boat captain got involved in other ferrying activities and forgot to pick us up for a day.  

It was the month of March, and it was cold and getting colder as the sun set.  We were -- temporarily -- stranded in the extinct, eroded volcanic cone that makes up Isla El Muerto ... the Island of Death.   

We were not alone.  One denizen of Isla El Muerto is the rare and locally endemic El Muerto Island Speckled Rattlesnake (Crotalus muertensis, the "viper of death"), found only on this island.  Here, this little-known serpent is often encountered around beach cobble, where we made our temporary bivouac.  Interestingly, this snake is a dwarf form of the mainland Speckled Rattlesnake (Crotalus mitchelli) found along the Baja Peninsula and southwest U.S.  Organisms stranded on islands often evolve into smaller forms, a process called insular dwarfism.  Insular dwarfism is an adaptation to more limited resources found on islands -- and was a future that this stranded traveler wished to avoid.  

According to the Historical Society of Southern California, Isla El Muerto was named for a rather gruesome situation:

This is the story an old Californian, who had been a sailor on a hide drogher ... told:  Away back in the early years of the present [19th] century some fishermen found the dead body of an unknown white man on the island.  There was evidence that he had reached it alive, but probably too weak to attempt the crossing of the narrow channel to the main land.  He had clung to the desolate island, vainly hoping for succor, until hunger, thirst and exposure ended his existence.  He was supposed to have fallen overboard at night from some smuggler, and to have been carried in by the tide.  From the finding of the body on the island, the Spaniards named it Isla del Muerto - the Island of the Dead, or the Isle of the Corpse.  

In due time we were rescued and, thankfully, avoided the fate of the island's namesake, including avoiding any deadly encounter with the island's dwarf vipers.  

Information:
    Annual publication of the Historical Society of Southern California and Pioneer Register Los Angeles.  1900.  Volume V.