Overview

Brief Summary

Introduction

Species of Leachia are easily recognized by the straight cartilagenous, tubercular strip on the mantle that arises from each point of funnel-mantle fusion, the slender, tapering mantle and the terminal fins with a combined oval shape.

Figure. Ventrolateral view of the antrior region of Leachia dislocata showing a transparent, cartilagenous strip bearing tubercules (arrow). Tubercules can be difficult to see because of their transparency. Photograph by R. Seapy.

Leachia species, however, are not easily recognized. Many names exist in the literature and most have poor descriptions associated with them and are based on paralarvae. At present, geographical location is one of the most important characteristics used in identification. The type localities of the named species are:

Atlantic Ocean
  • Leachia atlantica - eastern North Atlantic, 36°, 10°W.
  • Leachia lemur - western North Atlantic, east of Cape Hatteras, 35°N, 73°W,.
  • Leachia sp. A - western South Atlantic, 39°S, 53°W.
Indian Ocean
  • Leachia cyclura - south Indian Ocean, 37°S 33°E.
Pacific Ocean
  • Leachia danae - (Gulf of Panama).
  • Leachia dislocata - off Southern California, eastern temperate Pacific.
  • Leachia pacifica - south Pacific Ocean, 15°S, 168°W

Brief diagnosis:

A cranchiin...

  • with one cartilagenous strip bearing tubercules on the mantle originating at each point of funnel-mantle fusion.

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Comprehensive Description

Characteristics

  1. Tentacles
    1. Median suckers of tentacular club greatly enlarged.**

      Figure. Oral view of the tentacular club of Leachia dislocata, 136 mm ML. Drawing from Young (1972).

  2. Head
    1. Eyes stalked in paralarvae.

  3. Funnel
    1. Funnel valve absent.
    2. Funnel organ: dorsal pad U-shaped with 3-7 papillae.

  4. Mantle
    1. Single tuberculate cartilagenous strip on mantle originates at each funnel-mantle fusion.*

  5. Fins
    1. Fins barely unite posterior to gladius (transversely elliptical in combined outline).

  6. Photophores
    1. Each eye with 5-21 oval photophores depending on species.
    2. Photophores on tips of arms III in mature or nearly mature females.
*Unique feature in family.
**Unique feature in family where suckers unmodified (not hooks or hook-like suckers)

Comments

This is the only genus in the subfamily Cranchiinae with paralarvae that have stalked eyes. Characteristics are from Voss (1980).

Comparison of species

Figure. Comparison of the structure of the mantle tubercular strips among five of the species. A - Leachia lemur, north Sargasso Sea, 42 mm mL. B - Leachia atlantica, subtropical North Atlantic, 54 mm ML. C - Leachia dislocata, off California, 34 mm ML. D - Leachia danae, eastern tropical Pacific, 53 mm ML. E - Leachia pacifica, off Hawaii, 41 mm ML. Drawings from Voss, et al. (1992, p. 191).

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Distribution

Vertical distribution

Off Hawaii, L. pacifica has a peculiar vertical distribution pattern which may prove to be common within the genus. Small squid are found in near-surface waters. As sexual maturity approaches, the squid undergoes an abrupt ontogenetic descent. At depths greater than 1000 m males and females become mature. Large photophores develop on the tips of the third arms of females and these are, presumably, used to attract males at great depths where the risk of predation is low.

Figure. Vertical distribution chart of L. pacifica, Hawaiian waters. Captures were made with both open and opening/closing trawls. Bars - Fishing depth-range of opening/closing trawl. Circle - Modal fishing depth for either trawl. Blue color - Night captures. Yellow color - Day captures. Chart modified from Young (1978).

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Ecology

Habitat

Depth range based on 290 specimens in 8 taxa.
Water temperature and chemistry ranges based on 283 samples.

Environmental ranges
  Depth range (m): 18.5 - 3500
  Temperature range (°C): 2.459 - 27.746
  Nitrate (umol/L): 0.120 - 43.585
  Salinity (PPS): 33.694 - 36.637
  Oxygen (ml/l): 0.109 - 6.258
  Phosphate (umol/l): 0.027 - 3.314
  Silicate (umol/l): 0.705 - 105.468

Graphical representation

Depth range (m): 18.5 - 3500

Temperature range (°C): 2.459 - 27.746

Nitrate (umol/L): 0.120 - 43.585

Salinity (PPS): 33.694 - 36.637

Oxygen (ml/l): 0.109 - 6.258

Phosphate (umol/l): 0.027 - 3.314

Silicate (umol/l): 0.705 - 105.468
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Life History and Behavior

Life Cycle

Life History

The paralarvae of the genus have a very distinctive appearance. A paralarva has a very long, slender brachial pillar and a pointed tip to the gladius. Paralarvae of Leachia were originally placed in the genus Pyrgopsis and are now often referred to as pyrgopsis paralarvae.

Figure. Dorsal and ventral views of paralarval L. pacifica, 7.9 mm ML, Hawaiian waters, original.

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records:4
Specimens with Sequences:3
Specimens with Barcodes:3
Species:3
Species With Barcodes:2
Public Records:2
Public Species:1
Public BINs:2
Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

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Barcode data

Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

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Wikipedia

Leachia

Leachia is a genus containing six species of glass squids. The genus is divided into two subgenera: Leachia and Pyrgopsis.

Members of this genus live in tropical and sub-tropical waters worldwide. The mantle is up to 20 cm long in the largest species. Leachia are characterised by the presence of two parallel ridges bearing raised cartilage spikes, which run along the underside of the body near the head. They have large round fins, 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 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[edit source | edit]

Genus Leachia

References[edit source | edit]

  • Norman, M. 2000. Cephalopods: A World Guide. Hackenheim, ConchBooks, p. 158.
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