Эрдэмтэд Коста Рикагийн Номхон далайн гүнээс олон жилийн турш судлаачдын анхааралд өртөөгүй байсан “Rhinochimaera costaricana” нэртэй сүнс загасны шинэ төрлийг олж тогтоолоо.
Тус загасны гурван эрэгчин сорьцыг 2000-2023 оны хооронд далайн 390-787 метрийн гүнээс цуглуулсан боловч урьд нь бусад төрөлтэй андуурч байжээ. Коста Рикагийн Загас агнуур, загас үржүүлгийн хүрээлэн (INCOPESCA), Коста Рикагийн их сургууль болон Бразилийн Парагийн холбооны их сургуулийн судлаачид орчин үеийн генетикийн шинжилгээний аргаар уг амьтныг шинэ төрөл болохыг баталсан байна. ДНХ-ийн шинжилгээгээр тус загас бусад “Rhinochimaera” төрлийн загаснаас 3.9-4.7 хувийн ялгаатай болох нь тогтоогджээ.
Судлаачид 90 гаруй өөр төрлийн загасны биеийн хэмжээстэй харьцуулалт хийснээр “Rhinochimaera costaricana”-г бусдаас ялгах биеийн онцлог шинжүүдийг тодорхойлсон байна. Тус загас нь ойрын төрөл зүйлүүдтэйгээ харьцуулахад богино хошуутай, нурууны сэлүүр нь илүү өндөр, нурууны хоёр сэлүүрийн хоорондох зай илүү өргөн, сүүлний хэсэгт байрлах товруу багатай зэрэг ялгаатай шинжүүдтэй аж.
Энэхүү нээлт нь далайн гүний экосистемд өнөөг хүртэл бүрэн судлагдаагүй олон зүйл оршин байдгийг харуулж байна. Генетикийн шинжилгээний дэвшилтэт аргууд нь музейн цуглуулгад хадгалагдаж байсан сорьцуудыг дахин судалж, шинэ зүйлүүдийг илрүүлэх боломжийг бүрдүүлж байгааг эрдэмтэд онцоллоо.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
A new deep-sea shark, Rhinochimaera costaricana, has been identified off the Pacific coast of Costa Rica. The species, a type of ghost shark, had gone unnoticed for decades despite being collected several times.
For years, Costa Rica’s deep Pacific waters have been sampled only occasionally, often leaving gaps in biological records. Scientists already suspected that these habitats held unusual species, but many of them were difficult to separate from known ones using older methods.
That changed with the use of modern genetic tools, which helped researchers re-examine older specimens such as this ghost shark. According to the study published in Zootaxa, this combination of field collection and DNA analysis led to the formal description of a species that had been hiding in plain sight.
Specimens Collected Over More Than Two Decades
The identification of Rhinochimaera costaricana is based on three male specimens collected between 2000 and 2023, at depths ranging from 390 to 787 meters. As reported by scientists from Costa Rica’s Fisheries and Aquaculture Institute (INCOPESCA), these ghost sharks had been stored in collections without being recognized as a separate species.
The work brought together INCOPESCA, the University of Costa Rica, and the Federal University of Pará in Brazil. As explained by the authors of the Zootaxa study, the long time span between collections made the analysis more complicated, but also helped confirm that the same pattern appeared across multiple individuals.
Genetic testing proved decisive. The paper said that DNA comparisons showed a divergence of 3.9% to 4.7% from other known Rhinochimaera species, a level that supports classification as a distinct species within this group of cartilaginous fishes.
Shark Structure Differences
To confirm the findings, researchers compared 49 body measurements from the Costa Rican specimens with data from more than 90 individuals representing known species in the same genus. According to the research team, such a broad comparison was necessary because long-nosed chimaeras often look extremely similar at first glance.
Several physical traits consistently set R. costaricana apart. It has a shorter snout than its closest relatives, a taller first dorsal fin with a more pronounced spine, a wider gap between its two dorsal fins, and fewer tubercles along the tail region.
These differences are subtle, but they appear consistently across all examined specimens. In this group of deep-sea cartilaginous fish, small morphological changes are often what separate one species from another.
An Ocean Still Full Of Unknown Species
The name Rhinochimaera costaricana refers directly to Costa Rica, where all known specimens were collected. And the naming also reflects the growing role of local institutions in studying deep-sea biodiversity.
The discovery also underlines how limited current knowledge remains of ecosystems beyond the continental shelf in the eastern Pacific. Even in areas that have been sampled for years, species can still go unnoticed, often because they were previously grouped under other classifications.
As noted by the scientists involved in the study, modern genetic sequencing is now allowing researchers to revisit older museum collections and identify distinct lineages that were once overlooked.
The case of this ghost shark shows that the deep ocean is still far from fully catalogued, with each new analysis revealing how incomplete the picture remains.
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