Currently consisting of 12 species, this genus is typically found at the water surface in tropical and subtropical ocean regions, and has both low nutrient requirements and salinity sensitivity.

All species in the genus have a theca; 29 membrane-bound armored plates with anywhere from 2 to 6 spines protruding from the cell.

Due to its bioluminescent capabilities, the type species of this genus, Ceratocorys horrida, has many practical applications.

It is also sensitive to environmental molecules; by measuring the bioluminescent response it can be used in rapid toxicity tests to detect the levels of different contaminants in water systems.

As an example, Matzenauer in 1933 described a "new species" of Ceratocorys that he called C. hirsuta, but the figures drawn very closely resembled a C. horrida cell lacking two of its spines.

[7] The organisms in this genus are all marine species and live in tropical and subtropical ocean regions.

They are also considered oligotrophic organisms with low nutrient requirements, having been found in regions where the phosphate content of the water was <10 mg/m3.

Since these organisms are photosynthetic and require sunlight to make food, they are most often found at the surface of the water[7] The type species C. horrida is very widespread, having been found in the Atlantic, Pacific, Mediterranean, Indian, Red, and Arabian Oceans.

The distribution limits of this species are sharply marked by the 19 °C isotherm, rarely ever appearing where the surface temperature is below 19 °C (Fig.

[7] C. armata likely has a similar range to that of C. horrida, though is slightly more limited to warm water, and is also rarer (Fig.

[7] C. reticulata is a distinctly tropical species and is even more limited to higher temperatures than C. horrida or C. armata (Fig.

[7] C. gourretii is a widespread but rare tropical species, even more restricted to warm waters than C. bipes and having never been found anywhere with surface temperature lower than 22.3 °C (Fig.

[7] C. skogsbergii is found in the southwestern Pacific, but is such a rare tropical species that no significant distributional correlation can be made (Fig.

[11] Due to the nearly ubiquitous presence of Ceratocorys in the oceans, it is ecologically important as a primary producer, though what organisms it specifically interacts with is not well known.

[15] The light is produced in specialized organelles known as scintillions which contain both the substrate luciferin and the enzyme luciferase.

When the cell is agitated, a series of reactions leads to a decrease in pH in the scintillion organelles, changing the luciferase conformation and allowing it to bind to luciferin, which causes the flash of light.

Anterior to this is the left sulcal plate that forms the posterior edge of the flagellar pore.

The theca of the genus is typically smooth or wrinkly with the exception of C. reticulata, which, as its name suggests, has a heavily reticulated plate texture.

There are also the ventral and dorsal body lists, which on C. horrida and C. gouretti have long spines not found in any other species in the genus.

C. bipes is the only species with two antapical spines, C. skogsbergii and C. gouretti have three, and C. horrida, C. armata, C. reticulata, and C. aultii all have four.

When cultured in still water, >80% of the population is considered "long-spined" with spines almost one cell diameter in length.

Reduction of spines is due to material resorption during endoskeleton transformation rather than as a result of cell division.

Once the water is returned to still conditions, the population will slowly recover back to being majority "long-spine" cells.

This is because the long spines provide more surface area, allowing the cell to take advantage of the viscosity of the water to reduce sinking.

The "short-spined" morphotype's reduced swimming and faster sinking rate is likely an adaptation to avoid turbulent surface conditions and potential cell damage.

[13] The dinokaryon is U-shaped and located in the posterior of the cell in at least C. malayensis; there has been no description of the shape of the nucleus in other species in this genus.

[17] Due to its bioluminescent capabilities and sensitivity to different environmental molecules, C. horrida has been used by rapid toxicity tests like QwikLite to detect levels of different man-made contaminants and toxins in aquatic systems by measuring the reduction in light production of the organisms.

[7] Furthermore, its sensitivity and inability to stand low temperatures makes it unlikely to indicate waters of tropical origins far from the source point.