"Potato Chips for Our Dogs"

(Dickson/Chronicle photo)

Bolinas Beach was covered with jellyfish-like velella velella yesterday:

Velella velella are most commonly found on Northern California beaches in spring or early summer, according to scientists at Point Reyes National Seashore. The oval-shaped creatures are related to jellyfish and are typically bluish in color, measuring up to 4 inches long.

“When the prevailing winds shift, such as during a storm, the Velella are driven towards the coast, where they often are stranded on beaches in great numbers,” according to the national seashore’s website. “As the Velella dries out on the beach, it becomes brittle and transparent, looking like a cellophane candy wrapper.”

One velella velella, aka "by-the-wind sailor" due to its
functional sail on top (Bedolfe/One World One Ocean)

As a Southern California native, [retired professor Del] Dickson said he was familiar with Velella velella but had never seen them in such abundance. He said his German shepherd and Cairn terrier excitedly snacked on the sea creatures, which have a small disc of cartilage surrounded by a translucent sail-like structure.

“We call them potato chips for our dogs,” he said.

The sail is not manipulable, so the by-the-wind sailor, as the name indicates, goes where the wind takes it, even if it means to its doom.

Your humble blogger found velella velella to be interesting, but what piqued his interest was its name. How many other creatures have such repetitive names? Grok said these are tautonyms:

Living things with repetitive names, like *Velella velella*, are relatively rare but not unheard of in scientific nomenclature. These names, where the genus and species are identical, are called tautonyms. Tautonyms are allowed in zoology under the International Code of Zoological Nomenclature (ICZN), but they are prohibited in botany under the International Code of Nomenclature for algae, fungi, and plants (ICN). This means that repetitive names can only occur in animals, not plants, fungi, or algae.

Some well-known examples of tautonyms in the animal kingdom include:

*Gorilla gorilla* (Western gorilla)

*Rattus rattus* (Black rat)

*Bison bison* (American bison)

*Gulo gulo* (Wolverine)

*Meles meles* (European badger)

*Velella velella* (By-the-wind sailor)

Determining an exact number of living things with tautonyms is challenging because no comprehensive, up-to-date global list specifically tracks this across all animal species. Taxonomy is a dynamic field, with species being discovered, reclassified, or synonymized regularly. However, we can estimate based on known patterns and examples.

Zoologists estimate that there are around 1.5 to 2 million named animal species as of recent years (with millions more potentially undiscovered). Tautonyms are a small subset of these names, often arising when a species is the most representative or only known member of its genus at the time of naming. Based on anecdotal evidence and lists compiled by taxonomists, there are likely a few hundred tautonyms in zoology. For instance, a casual survey of mammals, birds, reptiles, and invertebrates yields dozens of examples (e.g., *Canis canis* for a wolf species, *Iguana iguana* for the green iguana, *Bufo bufo* for the common toad), but this is far from exhaustive.

Given that *Velella velella* is a hydrozoan (a type of cnidarian), and considering the diversity of marine invertebrates, it’s plausible that many tautonyms exist among lesser-known groups like jellyfish, worms, or mollusks. However, without a centralized database specifically for tautonyms, a precise count remains elusive. A reasonable estimate, based on expert discussions and taxonomic trends, suggests there could be 200 to 500 tautonyms among living animal species today.