C.scaber does not emit light
C.ales is the only shellfish known to flash at the moment
This is a particularly nutritious and subversive science popularization
Biological classification
Realm: Animal kingdom Animalia
Phylum: Mollusc phylum Mollusca
Class: Bivalvia
Order: Fox clam order Limida
Family: Limidae of the family Clamidae
Genus: Ctenoides of the genus Fox
Species: C. ales
English Name:
electric flame scallop,disco scallop,electric clam, disco clam
This time to introduce the diving often seen when the "lightning shell" is also often called "flame shell", first do not rush to call it so, Xiaobian consulted a lot of information to have a subversive discovery, at present you can find in addition to this article almost all Chinese science science have defined the wrong species of lightning shell.
Lightning shells belong to the genus Fox Shell, which has four brothers who are almost identical in appearance and extremely difficult to distinguish with the naked eye.
△图片来源于Li, J., Dougherty, L. F. Molecular Phylogeny and Morphological Distinctions of Two Popular Bivalves, Ctenoides scaberandCtenoides mitis.
At present, most of the Chinese data point out that the lightning shell/flame shell is C.scaber, (scaber is also called scabra) and some are also called Lima scaber (scabra), in fact, this is completely wrong, C.ales is the only shellfish that is currently known to flash.
Most sources indicate that C. Scaber (scabra) does not shine at all. The following figure proves this:
△图片来源于Dougherty, L. F., Johnsen, S., Caldwell, R. L., Marshall, N. J. (2014). A dynamic broadband reflector built from microscopic silica spheres in the ‘disco’clam Ctenoides ales.
And the extranet data shows that C. scaber (scabra) is commonly known as Flame Scallop, can be translated as flame shell, but we now know, they do not flash, in order to increase accuracy, we do not need to use the commonly used "lightning shell" or "flame shell" in our article to call them, temporarily in the C.ales English name literal translation of "electric shell" or "disco shell" to call.
Well, after this important clarification, we can happily introduce our protagonist C. ales.
It lives in the central Waters of the Indo-Pacific Ocean and prefers tropical warm waters. They can survive at a depth of up to 20 meters, they need sunlight but like to hide in caves such as rocky corals. It is a filter-eater and survives by eating plankton. They can swim freely in the water, swimming in the opposite direction of the shell opening, and they rely on fanning two shells to propel themselves forward. When the electric shell finds the crevice of the rock of his choice, he drills into it in one breath and then secretes a foot filament (byssus) to fix himself. If they want to move, they can also break off these foot filaments and jump out of the cave.
△ The image of the foot silk is from reefs.com By James W. Fatherree
For many years, it has been thought that the flash of electric shells, like some seaweeds and jellyfish, relies on fluorescent cells to emit biological fluorescence, until recent years it has been confirmed that electric shells themselves do not generate electricity and do not emit light. It mainly relies on absorbing light and reflecting to create "lightning". They don't glow without light.
The edge of the coat membrane of the electric shell can be divided into several parts:
The white part of the outermost edge filled with nano-spheres composed of silica is also the most reflective part of all wavelengths, and the white part efficiently reflects blue-green light (400-500 nm wavelength) out. The crimping edges of the coat membrane are constantly rolling, very fast, several times per second, which is why we can see the effect of lightning.
The use of silica reflection to emit light is extremely rare in the ocean, first of all, the animals in the ocean can purposefully secrete silica is rare, more familiar examples such as sponges, can secrete silicified bones, such as limpets (Limpets) of the tooth tongue (radula) there is hard silica, used to grind food. Single-celled biodiphenyl diatoms have a silica cell wall and can also reflect light, but are far from comparable to full-band reflections such as electric shellfish.
It is not yet certain what the flash of the electric shell is, but some experiments have found that the flash speed of the electric shell increases under the condition of simulating the enemy passing, but it is not clear whether it is to scare the enemy, or to be frightened by the enemy' heart pounding; or perhaps to be more attractive during mating; or to use light to attract phototropic plankton to approach themselves, so as to have a full meal.
Some shellfish have eyes, and they are distributed in a circle on the outside of the mantle membrane. The eyes of the electric shell are distributed at the edge of the mantle membrane, the root of the tentacles, and it is difficult to observe the eyes in the absence of flash, but their eyes are also reflective, and can reflect red light under the flash, and the position of the eyes can be more obviously seen, with a total of 40 eyes.
△ Eyes of different shellfish, picture from reefs.com By James W. Fatherree
△ Electric shell eyes, in the flash will reflect red light. Image credit: Lindsey Dougherty. Flashing in the 'Disco' Clam Ctenoides ales (Finlay, 1927): Mechanisms and Behavioral Function
Zoom in a little to see those red dots:
△ Image from Lindsey Dougherty
△ The picture comes from www.aau.edu
Some scientists have done a despicable experiment, using a mantis shrimp to scare electric shells, and found that the water environment around electric shellfish, sulfur content increased significantly, in order to infer that they also have the ability to secrete acidic toxic substances, used to resist the enemy. Their long tentacles are also covered with poisonous mucus, so don't be curious to touch them.
Special thanks▽
Marine Bivi
References ▽
Li, J., Dougherty, L. F. Molecular Phylogeny and Morphological Distinctions of Two Popular Bivalves, Ctenoides scaber and Ctenoides mitis.
Dougherty, L. F., Johnsen, S., Caldwell, R. L., Marshall, N. J. (2014). A dynamic broadband reflector built from microscopic silica spheres in the ‘disco’clam Ctenoides ales. Journal of the Royal Society Interface,11(98), 20140407.
Dougherty, L. (2016). Flashing in the'Disco'Clam Ctenoides ales (Finlay, 1927): Mechanisms and Behavioral Function(Doctoral dissertation, UC Berkeley).
https://www.mentalfloss.com/article/60937/meet-flashing-toxic-disco-clam
https://www.nature.com/news/how-the-disco-clam-got-its-flash-1.15462
https://www.nationalgeographic.com/news/2015/1/150106-disco-clams-animals-science-oceans-light-predators/
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