WINGS? ON A GASTROPOD SHELL

Can wings can be present on a snail snail? The answer is, of course not!  But, this post concerns the so-called “winged triton” seashell, more formerly known a Gyrineum perca. In scientific description, these so-called “wings” are more properly referred to as varices. They are aligned  along the sides of the shell, and they probably provide stability on the ocean floor for the shell. The growth of varices on shells is referred to as “episodic,” growth; that is to say, it is intermittent but fast. Initially, a thin-flexible expansion of the shell is built, and as this material is secreted, it is mineralized and gradually thickened, over a period of several days. The gastropod otherwise remains inactive and concealed until the new shell material is hardened (Vermeij, 1993). 

For you “old timers,” this particular seashell was colloquially known as the “winged triton” or “maple-leaf triton.” For awhile, it was previously referred to in the scientific literature as Apollon perca or Biplex perca, but if you regularly read my posts, you will be fully aware that the names of sea-shells are commonly in a state of flux these days; mainly, because of new DNA data about these animals.

A

B

C

Gyrineum (Biplex) perca, length 55 mm, width 45 mm, thickness 16 mm.apertural view. A) apertural view. B) abapertural (back) view. C. Right-side view. No Locality data available.

Another specimen of Gyrineum perca: length 52 mm, width 40 mm, thickness 15 mm. This second specimen has an operculum [used to close off the aperture from predators]; the operculum consists of horny [=organic material which is not calcified]. Locality data not known.

According to WoRMS [World Register of Marine Species], the current classification of this seashell is:

Class Gastropoda

Order Littorinimorpha

Family Cymatiidae

Genus Gyrineum

Subgenus Biplex

Species perca (Perry, 1811)

The shell of Gyrineum (Biplex) perca ranges from 31 to 100 mm (1.2 to 3.9 inches) in length. The shell, which is white, yellowish, or pale brown, is quite flattened, with a large flange (“so-called wings”) along its two sides.

The modern-day distribution of Gyrineum (Biplex) perca is eastern Africa to Japan. It is essentially  confined to warm (tropical) waters (Wikipedia, 2024). 

Gyrineum is one of the 24 known genera of family Cymatidae Link, 1807. To view some of the species of Gyrineum that resemble Gyrineum perca (there are at least four other such species)—the differences being in the shape of the wings (flanges); for more information, see the following website: https://www.jaxshells.org/gryrineum.htm 

References Cited:

Beu, A.G. 1998. Family Ranellidae. In Mollusca The Southern Synthesis, Part B. Fauna of Australia Volume 5. Pp. 799-802. CSIRO Publishing, Melbourne, Australia 

Vermeij, G.J. 1993. A natural history of shells. Princeton Science Library. 207 pp.

Wikipedia. 2004.

WoRMS. 2024. World Register of Marine Species [https://marinespecies.org]

AN UNUSUAL SOUTHERN CALIFORNIA ORB-WEAVER SPIDER

Spiders, like other arthropods, have six legs. This blog post concerns a species of spider belonging to the order Araneae, family Araneidae, and genus Argiope (the orb-weaver spiders).

Orb-weaver spiders are the most common group of spiders in the world. Some of them can be bizarre-looking and very brightly colored. I recently found two specimens in my garden. Compared to other orb-web spiders found in southern California, they are unusual. Their bodies (carapaces) have a yellowish-brown color pattern. The exteriors have several rows of prominent bumps that protrude out over the ventral surface.

I checked what literature I have in my natural-history library, as well as online, and I determined that these spiders represent an unusual variety of Argiope argentata, a species that typically lives in New World tropical and temperate regions, especial in of Central America and South America. The specimens in my garden, however, have a less spectacular color pattern than most other Argiope argentata species, which can have patches of silver, black, red, yellow, green, orange and/or brown.

A

                                            

Dorsal view of specimen (A): length of spider approximately 2 inches long). Next, below, is the ventral view (B) of this same specimen (slightly out of focus). The prominent white, “zig-zag thread” = the stabilmentum, which was secreted by the spider. See the text for a discussion of the function of the stablimentum. [Note: this kind of spider positions itself upside down on its web. The wind was blowing when I took this picture, and I could not get a sharp-focus image of ventral (bottom side) of this spider].

B 

The last and third image (C), see below, is a ventral view of another, but smaller, specimen (length only1.25 inches). Its stabilmentum is also present (on the left side of this view). The web of this specimen was more complete than the other specimen. Both specimens were found in my garden, in northern Los Angeles County, southern California. 

C

                               

Orb spiders typically have very large and complex orbicular (circular) webs. The web of the first spider photographed above (images A and B), was only a very partial one (i.e., a small lenticular-shaped remnant of its recently damaged web). I returned the next day to view the spider, again and it and the web were gone, except for a few filaments. Orb-weaver spiders are known to routinely destroy their own webs and create new ones. That is most likely the best  explanation for the sudden disappearance of its web. The web of the second specimen was a more complete (but still small) classic orb-spider web. 

Like other orb-web spiders, the ones found in my garden positioned themselves upside down in their web where they wait for their prey (e.g., mosquitoes) to get trapped.

note: a comment on the purpose of the stabilmentum. Some experts speculate that it is to make the web visible to birds that might otherwise fly into the web and, thereby, destroy it. This type of structure is commonly made by orb spiders.

Sources of Information:

Conrad, J. 2014. A blog site. Naturalist Newsletter. https://backyardnature.net. 

Levi, H.W. and Levi L.R. 1968. A guide to spiders and their kin. A Golden Nature Guide, New York, 160 pp.

Nicky Bay. Orb-weavers (Araneidae checklist)-Macro photography of many species, some with unbelievable shapes and colors). An online website. 

A GIANT-SIZED MIOCENE FOSSIL BARNACLE FROM CALIFORNIA

On the west side of the San Joaquin Valley, central California, near the town of Coalinga, outcrops of the shallow-marine Santa Margarita Formation contain locally abundant, giant-sized (several inches tall and wide) barnacle fossils. Identifications as to their genus and species have been inconsistent (Cote, 1991:p.158). Detailed study is needed to resolve their exact generic identification. In one of my previous blog posts (Nov. 11, 2017), I briefly mentioned these large barnacles and photographed the same cluster of specimens that is also used in this current blog post. 

Some specimens of this large (several inches tall and wide) barnacle genus/species have, in a few cases, been misidentified as fragments of mammoth bone or even as rudistid bivalves (note: these particular bivalves went extinct at the end of the Cretaceous). 

Top view of an individual specimen of Tamiosoma gregaria Conrad, from the Santa Margarita Formation, Coalinga area.

Side view of the same specimen.

Basal view of the same specimen.

Top view of a cluster of T. gregaria (7 inches wide and 6 inches tall) from the same locality as the specimens shown above. 

REFERENCE CITED

Cote, Russel. 1991. Paleontology of the Santa Margarita Formation. California State University, Northridge. This master’s thesis is available for free online. 

PONDEROSA LEMON (BIGGEST LEMONS EVER)

The gigantic fruit of the ponderosa “lemon,” or Citrus x pyriformis, is the biggest citrus in the world. It is a hybrid of a pomelo and a citron, thus it is not a true lemon. It was probably derived from a cross between a wild citrus and a domesticated citrus, such as a variety of a bitter orange. It can weight as much as 5 pounds and is often the size of grapefruits. Furthermore, like other citrus, lemons are actually a berry. 

The example shown above is from northern Los Angeles County, southern California. Such plants are not native to this area; they have to be purchased from plant nurseries.

The tree from whence the giant fruit came from (i.e. after it was picked). You can see some regular sized fruit still on the tree.

Some other big "lemons" from the same tree (shown above). Although, these are large, they are not as big as the giant one shown above. These big "lemons" are in the process of growing into giants.

The fossil record of citrus fruit is is poor! The earliest fossils of citrus plants (in general) are of late Miocene age (8 million years ago) and  are found in southwestern China.

Reference Consulted: A blog by Jerry James Stone (2023).

WESTERN SPADEFOOT TOAD, TRANSVERSE RANGES, SOUTHERN CALIFORNIA

While doing geologic field work in the Transverse Ranges, just north of the San Fernando Valley in southern California, one day a few years ago, I came across something I had never encountered before or since. I was way off the “beaten track,” in a “wild” area, when I saw three toads sitting on a rock, next to a small stream–in a shady area. This particular area is not easily accessible to hikers, and that is undoubtedly the reason these toads were present. It is common knowledge that unspoiled “wild areas”) are becoming fewer and fewer these days (and sightings are rare–because of human encroachment. Furthermore, this toads is now considered to be an endangered species in this area, and I was fortunate to be able to see them. In addition, it was rare event because, I spotted them during the day, even though they are primarily nocturnal.

Phylum Vertebrata

Class Amphibia

Family Pelobatidae

Genus Spea [spea is Greek, meaning warty skin]

Species hammondii

Spea hammondii is a small (1.5 to 2.5 inches long) stout-bodied toad with short legs and warty skin. Their eyes are wide-set, with no bone buildup (boss) in between them. Their adult body often has four irregular light stripes and black blotches on their back. Their backs can be all brown or all gray. Their abdomens are white. A juvenile specimen I saw [illustrated here] was all green.

Three species of Spea are found in California: hammondii has the greatest geographic range as it occurs throughout California, as well as in northwest Baja California, Mexico. Another species occurs only in northeastern California (east of the Sierra Mountains) and another species occurs only in southeastern California.

                                          A

                                           B

A western spadefoot toad [A and B, two views of adults, both about 2 inches long; and C, view of a juvenile, about ¾ of an inch long] alongside a small creek, in the Transverse Ranges just north of San Fernando Valley, northern Los Angeles County, southern California. I did not measure exact dimensions because I did not want to disturb the animals in any way.

“A HORSE IS A HORSE, OF COURSE,” UNLESS IT IS A SEAHORSE

Seahorses are ray-finned fishes. They weight 7 ounces to 1 pound. The largest ones are up to 35 cm long.  They have a horse-like head, with elongate noses, and curled tails that are prehensile (= they have the ability to hold onto objects). Their bodies are covered with consecutive rings of interlocking bony plates. They also have tubular snouts and a small toothless mouth. They eat by suction. They no have stomach. The color of seashores can be brown to black, but they can have yellowish, reddish purple, or greenish patches. Seahorses have a ravenous appetite. Their eyes can move independently. During reproduction, the males carry the babies.  

Seahorses live one to five years in captivity. They can make good pets, but they have to have the right environment (e.g., their tanks holding at least 40 gallons of seawater). 

There are about living known genera and 225 species of seahorses. Their classification is as follows:

Phylum Chordata

Class Actinopterygii

Order Syngnathiformes

Family Syngathidae 

Genus Hippocampus (the word means horse). There are about 50 genera, and the most common one is Hippocampus. 

Seahorses branched most likely from “pipe fish," which have long and narrow bodies.” 

The earliest known fossil record of seahorses is middle Miocene (13 million years ago), in Slovenia, Europe (Zalohar et al., 2009). The skeletons are well preserved and look just like a modern seashore. There is no doubt that they are seashorses.

Three views (left, right, and front) of the skeleton of a typical Hippocampus seashorse, length 55mm (2.5 inches), width 10 mm (1.25 inches), and thickness 6 mm (1/8 inch wide). The skin of this specimen is not preserved, therefore, identification as to species was not possible.

The “weedy seahorse” or “leafy sea dragon.” (image modified from a picture in the “Eyewitness Books” Fish (p. 23). Specimens like the one illustrated here can be up to 12 inches (30 cm) in length.

Seashorses live mainly in warm waters in the Indian Ocean, Pacific Ocean (especially southern Australia) and New Zealand, and also in the Caribbean Sea. They like to live in areas where sea weeds are abundant, thereby allowing them to hide from predators.

REFERENCES CITED

Eyewitness Books (Fish), 1990. Alfred A. Knopf, New York, 64 pp.

Zalohar et al. 2009. Two new species of seahorses (Syngnathidae, Hippocampus) from the middle Miocene Tunjice Hills, Slovenia. Annales de Paleontolgie 95:21-26. 

Wikipedia. 2024.

TWO EXAMPLES OF SEA SLUGS (NUDIBRANCHS = “SEA HARES”)

Phylum Mollusca

Class Gastropoda

Order Nudibranchia

Family Tethydidae

Genus Tethys Linnaeus, 1767

Species fimbria

This group of gastropods is also called nudibranchs because they lack a hard shell. They are among the most unusual looking marine gastropods in the world! Their head is covered by a hood, and the upper part of their body has projecting external gills that can be brightly colored.

Tethys, which is one of the two living genera of this family, consists of three living species. One unforgettable example is Tethys fimbria, which lives today in the temperate waters of the Mediterranean Sea, as well as along the east coast of the Atlantic Ocean; from Portugal to the Gulf of Guinea (in western Africa). This animal crawls around on sandy and muddy bottoms, in relatively deep waters (i.e., below maximum diving depth for collectors using compressed air). But this gastropod migrates to shallower waters to spawn. It prefers to crawls around on the ocean bottom, but, if disturbed, it can swim. Tethys fimbria can grow up to 30 cm (12 in.) in length.

Figure 1. Sketch of an adult specimen of T. fimbria. Image is derived and modified from a Wikipedia image. I highly recommend that you go to Wikipedia to see amazingly beautiful images of this animal!

_________________________________________

Family Aplysiidae

Genus Aplysia

Species californica (Cooper, 1863)

This species of nudibranch is referred to as the “California Brown Sea Hare.” Adult specimens can be up to 40 cm long (16 inches) (Morris et al., 1980, p. 313) and weighing several kilograms; making it the largest known gastropod in the world. Juvenile specimens have no spots. This species is found all along the California coast, as well as that of Baja California and western Mexico (Wikipedia, 2024).

Figure 2. Sketch of an adult specimen of A. californica. Image is derived and modified from Morris et al. (1980, “page” P97 pertaining to the illustrations but not to the main text of their work, fig. 14.8a).     

Figures 3 and 4. An adult specimen, estimated 15 cm long (6 inches) of Aplysia californica in a southern California tide pool at Abalone Cove, Palos Verdes Peninsula, Los Angeles County. Images taken by Cathy Groves (affiliated with the Natural History Museum of Los Angeles County) and kindly provided by Lindsey T. Groves, Collection Manager of Mollusks, Natural History Museum of Los Angeles County, California. 

References Consulted

Linnaus, C. 1767. Systema Naturae, v. 1, 10^th edition. British Museum of Natural History, Regnum Animalae.

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Stanford University Press, Stanford, California, total 690 pp., including a separate section of only photographs, numbered P1-P200.

Wikipedia, 2004