Leachia is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 containing six species of glass squid

Glass squid

The family Cranchiidae comprises the approximately 60 species of glass squid, also known as cranchiid or cranch squid. Cranchiid squid occur in surface and midwater depths of open oceans around the world. They range in mantle length from to over , in the case of the Colossal Squid. The common...

s. The genus is divided into two subgenera

Subgenus

In biology, a subgenus is a taxonomic rank directly below genus.In zoology, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the generic name and the specific epithet: e.g. the Tiger Cowry of the Indo-Pacific, Cypraea tigris Linnaeus, which...

: Leachia and Pyrgopsis.

Members of this genus live in tropical and sub-tropical waters worldwide. The mantle

Mantle (mollusc)

The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...

 is up to 20 cm long in the largest species. The Leachia are characterised by the presence of two parallel ridges bearing raised cartilage

Cartilage

Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

 spikes, which run along the underside of the body near the head. They have large round finds, which often constitute 20-30% of the entire mantle length. Like most glass squids, members of this genus possess a ring of light organs around their eyes. Bioluminescent

Bioluminescence

Bioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in...

 cells produce light that cancels the shadow cast by their large eyes. Typical of cranchiid squids, juvenile Leachia species have stalked eyes. As they mature, females develop light organs on the ends of their third arm pairs. These are thought to be used in mating displays to attract males.

Classification

Genus Leachia

• Subgenus Leachia
  • Leachia (Leachia) cyclura
  • Leachia (Leachia) ellipsoptera
  • Leachia (Leachia) lemur
• Subgenus Pyrgopsis
  • Leachia (Pyrgopsis) atlantica
  • Leachia (Pyrgopsis) pacifica
  • Leachia (Pyrgopsis) rynchophorus