Bigeye chimaera

Photo by FishBase, Reyes, P.

​Let’s dive into this next diverse Chondrichthyan: a chimaera! The Bigeye chimaera, Hydrolagus macrophthalmus, is known from 590-1160 metres deep in their subtropical range. From in the eastern Pacific Ocean from Chile, they are a brown across their entire body with no other distinguishing markings outside of their fins having a blue tinge. 

With a slender body, black eyes, a long tail, and an intimidating-looking dorsal spine in front of their dorsal fin… it’s no wonder some people think of them as monsters! However, “Hydrolagus” actually is Greek for two works—‘hydr’ which means water and ‘lagos’ which means hare. It’s a water-hare! Less intimidating, right?
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Like other chimaeras, they are oviparous and lay horny eggs that will eventually hatch into young bigeye chimaeras. How long is the gestation period? We have no idea! In fact, we know little about this species—according to the IUCN it is, “the rarest and most poorly known species of chimaeroid.” There are only two specimens from the pre-abyssmal zone off central Chile. Due to this, the IUCN has assessed them as Data Deficient (DD).

WHAT DID YOU LEARN ABOUT THIS ANIMAL?

GLOSSARY

• Continental shelf: Extends from a continent underwater, resulting in a shallow-water area.
• Continental slope: The steep slope from a continental shelf to the ocean floor; usually around 20 km (12.4 miles) wide and made up of mud and silt substrate. It is an ideal area for deep sea fishing.
• IUCN: International Union for Conservation of Nature.
• Oviparity/oviparous: Where adult Chondrichthyans lay eggcases (also known as ‘mermaid’s purses) and the baby develops inside the egg before hatching.​

SAY HELLO!

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