These Tiny 'Monsters' of The Deep Sea Are Not What Scientists First Thought

We are constantly amazed by the mysteries that lie within the vast oceans of the world. This latest haul of deep-sea animals includes bulging torsos with spiky backbones, armorlike horns, and translucent bodies that are both strangely beautiful, and perplexing.
The creatures are found in the Gulf of Mexico and include a variety of strange beasts that have never been seen before.

It turns out that the strange creatures are not new species. These are the larval and juvenile forms deep-sea shrimps and prawns that live in the darkest and deepest parts of the oceans. This has been revealed by painstaking research.

Heather Bracken-Grissom is a Florida International University marine scientist and Carlos Varela a graduate student who wanted to identify a group of unique specimens using genetic tests.

Taxonomy is the classification of organisms in the tree of living things. It can be difficult at times.

The Gulf of Mexico is home to lobster and shrimp development stages. (Dant Fenolio/DEEPEND/RESTORE)

Scientists used to only have half-digested samples from fish, tuna, and dolphins. Or, perhaps more pleasant, one specimen, Cerataspis monstrosus. This larval form Plesiopenaeus Armatus is a deep-sea shrimp, which lives in the ocean's abyssal plains, up to 5,000m below the surface.

Bracken-Grissom stated that there are many instances when we have documented animals in their infant or larval stages, but have no idea what they become as adults." Bracken-Grissom made this statement at the 2012 discovery that reunited C.monstrosus and P. armatus.

Scientists might not realize it, but many deep-sea shrimp families are "fraught" with taxonomic issues. This is because some rare and uncommon larval stages have been incorrectly called new species or genera.

Bracken-Grissom, Varela and Varela matched 14 species of larval and juvenile animals to their adult counterparts with DNA barcoding. This is a technique which compares short segments from DNA taken from known and unknown specimens.

Scientists knew very little about the larvae of 10 deep-sea species before this study. It's easy to see why some of the specimens used in this study are less than an inch in length, roughly the size of your thumb.

Bracken-Grissom & Varela wrote that "for many groups, larval descriptions were missing or nonexistent, so this research represents a first-step of many to advance deep sea larval diversity."

The study included examples of the stages of development for crabs. (Dant Fenolio/DEEPEND/RESTORE)

They measured, measured, and described the curious creatures they collected during eight expeditions to the northern Gulf of Mexico. Many of them had never been seen before and some were difficult to raise in the lab.

They revealed a stunning array of juvenile and larval forms from different deep-sea shrimp species. This added new piece to the puzzle of their complicated life cycles, which in some cases may include nine or more larval stage.

One of the larval specimens was identified as belonging to the Alvinocarididae shrimp family that live in deep-sea cold spots. It was found at depths of 1,000 meters.

Another juvenile Funchalia villlosa was also identified. This species is known for making daily vertical migrations through water column. It ascends at night from depths around 2,600m (8,530 ft), to within 50m (160 ft), the surface to feed.

However, not all deep-sea shrimps can be considered transitory. Bracken-Grissom explains that many of these larvae can be found in open water between 200 and 1,000 meters [560-3,300 ft] and then settle on the deep-seafloor as adults.

Researchers say that matching adult forms with their infant forms is crucial in understanding how deep-sea shrimps and other crustaceans are at different stages of their lives and where they fit in the ocean's food web.

She adds that crustacean larvae are often the primary food source for small and big migratory fishes as well as cephalopods, cephalopods, and deep-diving marine mammal species.

Researchers suspect that these shrimp species are not well-known. They may have many larval stages, which can be affected by seawater salinity and temperature. More work will be required to study the secrets of deep-sea dwellers.

The journal Diversity published the research.