Gymnura lessae
Species of butterfly ray (Gymnura) From Wikipedia, the free encyclopedia
Gymnura lessae, or Lessa's butterfly ray, is a cartilaginous fish (batoid) species of butterfly ray (Gymnura). Native to the coastlines stretching from Massachusetts, US to the Gulf of Mexico and the Caribbean.[2] It is named after Rosângela Lessa, a prominent figure in shark and ray conservation.[3][4]
| Gymnura lessae | |
|---|---|
| |
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Order: | Myliobatiformes |
| Family: | Gymnuridae |
| Genus: | Gymnura |
| Species: | G. lessae |
| Binomial name | |
| Gymnura lessae Yokota & Carvalho, 2017 | |
Initially, G. lessae was thought to be the same species as Gymnura micrura, however and primarily because of internal morphological differences, Gymnura lessae was redescribed as a new species.[4]
Distribution and habitat
Gymnura Lessae is found on a long stretch of the eastern side of the US from Rhode Island to the Gulf of Mexico including Louisiana and Texas, US and Tamaulipas to Campeche, Mexico.[1] They occupy neritic environments, prefer sandy and muddy bottoms and reach a depth of up to 60 m (200 ft).[1]
Dietary habits
Gymnura lessae is a specialized teleost feeder who primarily eats drumfish and anchovies.[5] They tend to hide and sneak, and stun their prey with their pectoral fins.[5]
Variation in feeding pattern exists, largely driven by sex differences and seasonal changes.[5] Sex driven variation is due to size and seasonal changes primarily the result of differing prey communities.[5] Females are much larger at maturity, hence tend to eat larger prey.[5]
Reproduction and growth
Gymnura lessae is a viviparous[1] sexually dimorphic[6] fish. Females are larger (disc width(DW):460 mm (18 in)) than males (DW:340 mm (13 in)), however the latter reaches sexual maturity faster; although both exhibit rapid growth and high fertility.[6] This makes G. lessae resistant to exploitation putting it as both a stable population and a least concern species[1][6] as compared to many other rays that face threats of extinction.[6]
Morphology
Summarize
Perspective
Like many butterfly rays, G. lessae exhibits a diamond shape flat body, wide disk, and a short tail.[7][8] The external morphology such as color vary between the posterior and anterior sides of the body but also between members of the species and across species of Gymnuridae.[4] The posterior side is darker in tone and exhibits radial like projections apparent at the beginning of the wings and a much lighter tone in the anterior side.[4] Other distinguishing characteristics of G. lessae from other Gymnuridae, especially Gymnura micrura include pectoral girdle and hyomandibula cartilage variation.[4]
The overall size and physiology of brain at maturity is smaller and simpler in G. lessae than in other batoids.[8] The cerebellum exhibits less surface area to volume due to the reduction in foliation.[8] The positioning of some of the cranial nerves is given in this table:[8]
| Nerve (#) | Origin | Position with respect to a reference frame |
|---|---|---|
| Olfactory (I) | Telencephalon (T) | anterior to cerebrum |
| Optic (II) | Border between T and Diencephalon (D) | projects anterolateral to T/D border |
| Oculomotor (III) | Medial of D | projects anterolaterally to D |
| Trochlear (IV) | Lateral D | Projects laterally to D |
| Trigeminal (V) | Laterally to Medulla Oblongata (MO) | Projects laterally to MO |
| Abducens (VI) | Anteriorly to MO | Projects laterally to MO |
| Facial (VII) | Laterally to MO | Projects laterally to MO |
| Acoustic (VIII) | Laterally to MO | Projects laterally to MO |
| Glossopharyngeal (IX) | anteriorly to MO | Projects laterally to MO |
| Vagus (X) | Lateral border of MO | Projects laterally to MO |
| Accessory (XI) | ? | ? |
| Hypoglossal (XII) | ? | ? |
IUCN classification and human interactions
Under the IUCN model 3.1, G. lessae is considered a species with a stable population and no observed decline as of 2019, therefore was considered a least concern species.[1] The species is considered harmless to humans.[2] It isn't commercially targeted in the US however, it is consumed in some local communities.[1]
References
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