Halavi Guitarfish

The Halavi Guitarfish, Glaucostegus halavi, is a distinctive ray belonging to the family Glaucostegidae, commonly known as giant guitarfishes. These fascinating batoids are characterized by their unique flattened bodies that transition into a robust, shark-like tail, giving them their common "guitar" shape. Primarily found resting on sandy and seagrass bottoms, this species is a captivating sight for divers in its native range. However, the Halavi Guitarfish faces significant threats and is currently listed as Critically Endangered by the IUCN, with its international trade monitored under CITES Appendix II. This critical status underscores the importance of responsible diving practices and awareness for its conservation.

Identification

• Overall Shape: The Halavi Guitarfish possesses a characteristic flattened, guitar-shaped body that gradually tapers into a powerful, shark-like tail. Its body is elongated and relatively flat.
• Size: This species can reach a maximum length of approximately 1.71 meters (5.6 ft). Newborns are typically around 29–30 cm (11–12 in) in length.
• Head and Snout: It features a wide, short, and pointed snout with a rounded tip. The rostral ridges are joined along most of the snout's length, and the rostral cartilage is pale and translucent. Small eyes are present, with two short, widely separated skin folds distinguishing the spiracles located behind them. Five gill slits are visible on each side of the ventral surface.
• Coloration: The dorsal (upper) surface typically ranges from yellowish to greyish-brown and is generally unmarked, providing excellent camouflage against sandy substrates. The ventral (underside) surface is distinctly white.
• Skin and Thorns: The skin is covered in small denticles, giving it a rough texture, particularly along the rostral ridge, between the eyes, on the shoulders, and along the centerline of the back. Small thorns are present around the eyes, with a single larger thorn on each shoulder and a continuous row of thorns running along the medial ridge from the nape to the tail.
• Fins: The pectoral fins are broadly rounded and fused to the head, forming the flattened disc, with anterior margins that are straight or weakly convex. It has two large, well-separated dorsal fins with narrowly rounded apices. The caudal (tail) fin is triangular and lacks a defined lower lobe.
• Habitat and Behavior: Halavi Guitarfish are benthic, preferring sandy substrates and seagrass beds in tropical seas, found from very shallow waters to depths of at least 100 meters. They are known to venture into very shallow areas to feed on benthic invertebrates, such as small mollusks, crustaceans, and bony fish. While generally skittish around divers, they can occasionally be observed resting on the seabed at dive sites like Marsa Abu Dabbab, and are also encountered at Gorgonia Beach off Marsa Alam, Egypt. The Al Wajh lagoon in the northern Red Sea has been identified as a vital nursery and refuge for this species.

The Halavi Guitarfish (Glaucostegus halavi) is a fascinating ray species predominantly found in the warm, tropical waters of the Indo-West Pacific. Divers seeking this critically endangered species will typically encounter it in specific benthic environments, reflecting its preference for particular substrates and depths.

• Environment and Substrate: This species thrives in coastal and continental shelf ecosystems. It shows a strong preference for benthic habitats characterized by sandy substrates and seagrass environments. These areas provide both camouflage and foraging grounds for the guitarfish.
• Depth Range: Halavi Guitarfish are typically found from very shallow, inshore waters down to depths of at least 100 m. While they are often observed in shallow bays and seagrass flats, they also inhabit offshore areas of the continental shelf. One confirmed record noted an individual captured at depths of 28–30 m on a sandy substrate.
• Geographic Distribution: The primary distribution of the Halavi Guitarfish spans the northwestern Indian Ocean. This includes the Red Sea, the Gulf of Oman, the Arabian Sea, and extends from Kenya to India. There are also unconfirmed reports of its presence further east towards China. Occasional sightings have been documented in Levantine waters, and there have been a few confirmed records in the Mediterranean Sea, suggesting a potential, though uncertain, establishment via the Suez Canal.
• Ecosystem Associations: Within its preferred habitats, the Halavi Guitarfish is an integral part of sandy bottom and seagrass ecosystems. It is a benthic species, meaning it lives on or near the seabed, where it feeds on demersal invertebrates, such as shrimps, as well as small mollusks and bony fish. Females are known to approach very shallow waters to give birth, highlighting the importance of these nearshore environments for reproduction.

Dive sites like Marsa Abu Dabbab offer occasional opportunities to observe this unique ray, particularly in its favored shallow, sandy, and seagrass-rich areas.

The Halavi Guitarfish (Glaucostegus halavi) is a fascinating ray species for divers to encounter, primarily found in the Indo-West Pacific, including the Red Sea and Gulf of Oman. As a critically endangered species, observing one in its natural habitat is a special experience.

• Underwater Encounter Behavior
  This bottom-dwelling ray is typically found on sandy substrates and in seagrass environments, ranging from very shallow coastal waters to depths of at least 100 meters. Divers often observe them motionless, sometimes partially buried in the sand during the day, a behavior that helps them camouflage. While they can be encountered by divers and snorkelers, particularly in the Red Sea at dive sites like Marsa Abu Dabbab, the Halavi Guitarfish is generally considered skittish in the presence of humans. When approached, they may remain still, relying on their camouflage, or slowly swim away. Younger guitarfish, or early lifestages, are known to utilize very shallow nursery habitats, which, while offering refuge from larger aquatic predators, can expose them to avian predators like ospreys.
• Feeding Habits
  The Halavi Guitarfish is a benthic feeder, meaning it primarily forages on the seafloor. Its diet mainly consists of benthic invertebrates, small mollusks, crustaceans, and occasionally small bony fishes. They are known to venture into very shallow waters to feed, making them accessible to divers in certain areas.
• Social Structure
  Observations suggest that the Halavi Guitarfish is generally solitary. There is no current evidence to indicate complex social structures or schooling behavior for this species. Divers are most likely to encounter individual guitarfish rather than groups.
• Notable Seasonal Patterns Relevant to Divers
  For divers in the Red Sea, the reproductive season of the Halavi Guitarfish occurs from May to October. This species is aplacental viviparous, meaning the embryos develop inside the mother, nourished initially by a yolk sac and then by uterine fluid, with a litter size of up to 10 pups. Newborns measure approximately 29 cm. Shallow coastal areas, such as the Al Wajh Lagoon in the northern Red Sea, serve as vital nursery grounds for early lifestage Halavi Guitarfish. Divers visiting these regions during the reproductive season might have a higher chance of observing these smaller individuals in shallower waters, though caution should be exercised to avoid disturbing them.