In the Water: Fishes
Spotted eagle ray
Aetobatus narinari
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About
Like the birds they’re named after, spotted eagle rays are a magnificent sight to see soaring through the reefs of Saba. These cartilaginous fish are endangered globally, so catching a glimpse of one is a special and uncommon experience. They eat crustaceans and small fish, and can use their elongated snout as a shovel to dig little shellfish snacks out of the loose sand where they hide. When they find a buried bivalve, they use their large, flat, overlapping teeth to crack open shells and get at the nutritious meat inside.
Scientists can use the white spots on their navy-blue backs like fingerprints: Each spot pattern is unique, so individual rays can be identified by sight. Another way scientists study this species is by using GPS tags. Marine biologists across spotted eagle rays’ range plant monitors on individuals to keep track of their movements and better advocate for the protection of places that are significant for the species.
In Saba’s shallow waters, spotted eagle rays are most likely to be seen alone, but in deeper reefs they can gather in loose congregations of up to 16 rays as they travel between feeding grounds. At their largest, spotted eagle rays can grow to 5 m/16 feet from their nose to the tip of their tail, with a 3-m/10-foot wingspan. They use these significant wingspans to coast through the water, but they’ve also been known to try flying. Much like whales, spotted eagle rays have been observed breaching the surface of the water and leaping through the air in a dramatic display. It’s not yet known why they do this, but researchers suspect the behavior could help them to shake off remoras and other parasites.
This endangered species has a relatively slow reproductive rate, with a year-long gestation period during which their young hatch internally from eggs and are born as young rays. At most, mother rays give birth to a brood of four in a year. For this reason, fishing can have a significant impact on population sizes, and even though these fish aren’t targeted specifically as food, they’re sometimes an accidental casualty of bycatch. Luckily, official protections in locations like the Saba Bank National Park have been established to help this and other vulnerable species thrive in Saba’s waters.
This species is:
Native
Why that matters:
Native species are those that evolved in the region naturally, without human influence. That means they’re specifically adapted to Saba’s habitat, and play a key role in island biodiversity. When we lose native species, gaps appear in the ecosystem. That leads to cascades of additional extinctions, and to the loss of the ecosystem services (food, clean air and water, flood and coastal protections, and more) that we humans rely on.
Each spotted eagle ray has a unique pattern of spots, making individuals visually identifiable. Credit: @erichabisch, iNaturalist, photographed in the waters around St. Kitts and Nevis (CC-BY).
iNaturalist Observations
Where locals, researchers, and visitors have seen this species.
Google / Imagery © 2023 CNES / Airbus, Landsat / Copernicus, Maxar Technologies, U.S. Geological Survey, iNaturalist Map data @2023
This map shows geotagged observations of this species made on iNaturalist, the world’s largest community-science platform.
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Ask a Scientist
Question: How does plastic impact coral reefs?
Answer: Plastic pollution is one of the most pressing problems plaguing ocean ecosystems, and coral reefs are no exception. From macroplastics that spread coral diseases to fishing lines that entangle and damage the structural complexity of the reef — decreasing both fish abundance and diversity — pollution negatively impacts the entire coral reef ecosystem.
Dr. Hudson Pinheiro
Research Fellow, California Academy of Sciences
Related Content
Saba Conservation Foundation
Organization
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In the Water: Fishes