A study from the Monterey Bay Aquarium Research Institute has found that a majority of deep-sea animals are able to produce their own light. What's interesting is that the researchers conducted the first quantitative analysis of deep-sea bioluminescence, a progress from the usual qualitative observations.

The research done by Séverine Martini and Steve Haddock was published in the journal "Scientific Reports." They found that three quarters of the animals in Monterey Bay, California, can make their own light.

According to Science Daily, counting the number of bioluminescent animals in the ocean using only videos and photographs is not enough. This is because very few cameras are sensitive enough to capture the faint glow of these marine animals below 300 meters, or 1,000 feet, where the ocean is pitch black.

Moreover, most animals don't glow all the time because light takes up extra energy. It also attracts predators.

Due to these challenges, most previous estimates of the number of glowing animals were based on qualitative observations. This new study by Martini and Haddock is the first quantitative analysis of the numbers and types of individual glowing animals at different depths.

The researchers collated data on every animal larger than one centimeter that appeared in video from 240 dives by MBARI's remotely operated vehicles (ROVs). They counted over 350,000 individual animals, each of which has been recognized by MBARI video technicians using a vast database called the Video Annotation and Reference System (VARS).

This database has over five million observations of deep-sea animals. It has also been used as a source of data for over 360 research papers.

The observed animals were divided into five categories: definitely bioluminescent, highly-likely to be bioluminescent, very unlikely to be bioluminescent, definitely not bioluminescent and undefined. There were about 20 to 40 percent of animals in the "Undefined" category.

Séverine Martini noted that bioluminescence could be a major ecological trait on Earth. This is because the deep ocean is the largest habitat in the planet, in terms of volume.