Dyakia striata (Gray, 1834)
Quantula striata, also known as Dyakia striata, is a species of medium-sized, air-breathing, tropical land snail. It is a terrestrial, pulmonate, gastropod mollusk in the family Dyakiidae. This species appears to be unique among terrestrial gastropods in that it is bioluminescent: Its eggs glow in the dark, and juveniles and most adults give off flashes of green light. It is the only species in the genus Quantula.
The shell of this species is dextral (right-handed) in coiling. The shell of an adult snail is 16–27 mm in width. The umbilicus is narrow. The color of the shell is brown, shading to white underneath.
The length of the body is up to 5–6 cm. The dorsal part of the head and foot is dark brown in color. The ventral parts are creamy white in color. The eye tentacles are long, and the eye spots are large.
Quantula striata is the only terrestrial gastropod known to exhibit bioluminescence. This was not discovered until 1942, when it was reported by Dr. Yata Haneda (see also Haneda 1946), probably because the flashes are quite dim. The purpose of the snail's bioluminescence is not yet fully understood, but it is thought to have some relation to animal communication. Light is emitted by an organ known as the "organ of Haneda," located in the head-foot region of the adult snail. This organ consists of a 0.5 mm-wide cluster of giant cells  and is a part of the suprapedal gland. The snail flashes while it is moving, and half as intensely when it is feeding, and does not flash when it is inactive. Flashes lasts 0.5–6.0 s.
The light produced is yellow-green, with a wavelength of about 515 nm. The substance which produces it had not yet been identified. Isobe at al. (1991) stated that the fluorescent substance "may be similar to flavin".
The eggs of this species glow, and so do newly hatched snails. Juveniles can produce flashes of light, as can most, but not all, adults.
In Singapore these snails live in a variety of disturbed habitats, such as lawns, walkways and rubbish dumps, and like most land snails, they are observed more often after rain.
- Latia neritoides, a freshwater snail from New Zealand, is the only other pulmonate gastropod that shows bioluminescence.
- Baker, H. B. (1941). "Zonitid snails from Pacific islands. Part 3 and 4". Bernice P. Bishop Museum Bulletin. 166: 203–370.
- Tumpeesuwan C., Naggs F. & Panha S. (31 August 2007) "A new genus and new species of dyakiid snail (Pulmonata: Dyakiidae) from the Phu Phan range, northeastern Thailand". Raffles Bulletin of Zoology 55(2) Archived July 22, 2009, at the Wayback Machine: 363-369. PDF
- Daston M. M. & Copeland J. (1993) "The luminescent organ and sexual maturity in Dyakia striata". Malacologia 35(1): 9-19. abstract
- Isobe M., Yuakul D., Sigurdsson J. B., Goto T. & Lam T. J. (1991) "Fluorescent Substance in the Luminous Land Snail, Dyakia striata". Agricultural and Biological Chemistry 55(8): 1947-1951. abstract and PDF[permanent dead link].
- Counsilman, J. J.; Ong, P. P. (1988). "Responses of the luminescent land snailDyakia (Quantula) striata to natural and artificial lights". Journal of Ethology. 6: 1. doi:10.1007/BF02348856.
- Asia and the Pacific Islands - The World of Snails Archived April 4, 2010, at the Wayback Machine
- Isobe, M.; Uyakul, D.; Goto, T.; Counsilman, J. J. (1988). "Dyakia bioluminescence—1. Bioluminescence and fluorescence spectra of the land snail,D. Striata". Journal of Bioluminescence and Chemiluminescence. 2 (2): 73–79. doi:10.1002/bio.1170020204. PMID 3213594.
- Copeland J.; Daston, M. M. (1989). "Bioluminescence in the terrestrial snail Quantula (Dyakia) striata". Malacologia. 30 (1–2): 317–324.
- "On Quantula striata (Gray, 1834) a bioluminescence snail with a compilation of related works". Online "Archived copy". Archived from the original on November 6, 2009. Retrieved November 24, 2009.CS1 maint: Archived copy as title (link) Last change: 30 January 2007, accessed 27 November 2009.
- Copeland, J. (1988). "Optic nerve responses to light stimulation in the bioluminescent terrestrial snail, Dyakia (Quantula) striata". Comparative Biochemistry and Physiology A. 89 (3): 391–400. doi:10.1016/0300-9629(88)91046-8.
- Copeland, J.; Counsilman, J. J. (1986). "Neuroethological Studies of Behavior in the Land Snail Dyakia (Quantula) Striata". International Society for Neuroethology Abstracts. 1: 93.
- Copeland, J.; Counsilman, J. J.; Loh, D.; Chan, S. Y.; Tan, W. H.; Maneri, M. (1987). "Factors Affecting the Rate of Flashing and Loss of Luminescence in an Asian Land Snail Dyakia Striata". Veliger. 29: 394–439.
- Haneda, Y (1946). "A luminous land snail, Dyakia striata, found in Malaya". Seibutsu. 1: 294–298.