Ghost sharks, also known as chimaeras, are deep-sea fish belonging to the order Chimaeriformes. Despite their name, they are not true sharks but are closely related. Ghost sharks have a cartilaginous skeleton and distinctive features like elongated bodies, large eyes, and smooth skin. They inhabit deep ocean waters and feed on small fish and invertebrates. These mysterious creatures are often found at depths ranging from 200 to 2,600 meters.
The species originated around 420 million years ago in the Silurian period. According to the Shark Trust, they are closely related to sharks, skates, and rays. But, around 400 million years ago, they diverged from their common ancestor. To date, it’s believed that there are around 50 species of chimera around the world.
Appearance
Ghost sharks have a very interesting appearance. Their soft tapering bodies include a bulky head with a one-gill opening. They can grow to almost five feet in length, including their long tails (these tails are confined to only certain members of their species.) They have a cartilaginous skeleton, with smooth skin that lacks scales. Most of the time, they range in color from black to gray.
One of the shark’s most interesting features is its venomous spin in front of the dorsal fin. These spines are common to most chimeras.
Some closely resemble sharks, especially in their means of reproduction. They use “claspers” to internally fertilize female members of their species. They can also use something known as electroreception to find their prey. This is a process by which a fish is able to detect electrical stimuli.
Unlike sharks, their upper jaws are attached to their skulls. They also have different teeth. Sharks are well-known for their ability to replace their teeth throughout their life. Chimeras, on the other hand, have their pairs of long tooth plates that they use for grinding.
They have distinctive pectoral fins that are large and wing-like, aiding in their graceful movement through the water. Their dorsal fins are prominent, with the first often featuring a venomous spine for protection. The tail fin is long and whip-like, helping them navigate the deep-sea environment efficiently.
Of the many species of chimera, some of those most commonly recorded are Rabbitfish, Pale Chimaera, Smallspine Spookfish, Small-eyed Rabbitfish, and Large-eyed Rabbitfish.
The Rabbitfish can be found around the North Atlantic Ocean. But, others, like the Galapagos Ghostshark, are confined to smaller regions (such as only in the Galapagos Islands).
Habitat
Ghost sharks prefer to live in temperate ocean environments, near the ocean floor, at depths of around 8,500 feet or 2,600 meters.
There have been some instances in which scientists have confirmed sightings of ghost sharks at shallower depths, around 200 meters or 660 feet. For some species of chimera, it’s a more common occurrence to live and feed around this depth.
Chimeras live in all the oceans except the Arctic and the Antarctic. It’s common to find them around volcanic areas and in soft sandy, and muddy areas.
Diet
Ghost sharks primarily feed on small fish, crustaceans, and mollusks. They use their flat, grinding teeth to crush the hard shells of their prey, making them well-suited for a diet of bottom-dwelling organisms. Their ability to detect vibrations helps them locate food in the dark ocean depths.
Unlike typical sharks, their teeth are not replaced continuously but grow slowly over time. This adaptation suits their diet of bottom-dwelling organisms, allowing them to efficiently break down tough exoskeletons and access the nutritious insides.
Reproduction
They reproduce through internal fertilization. Males have specialized claspers, which are modified pelvic fins used to transfer sperm to the female. After fertilization, females lay leathery egg cases on the ocean floor.
These egg cases, often called “mermaid’s purses,” protect the developing embryos until they hatch.
The young ghost sharks emerge fully formed and ready to survive in their deep-sea environment.
Chimeras can likely live to around 30 years, with some studies suggesting longer. They reach sexual maturity fairly late in life and only give birth to a few young.
Threats
Ghost sharks are subject to several different parasites. These include Chimaericola leptogaster, a parasite that lives in their gills.
Today, it’s believed that Chimeras are threatened. There is not much information available about the species in general, mostly due to the depths they live in and overall scarcity. But, some studies have suggested that 8% of chimera species are threatened. There are currently 50 extant species. Some are only known from fossils.
There are only a few fisheries that target chimeras, mostly due to trawling. They can be a product of bycatch. This means that they’ve been caught in a net along with other marine creatures that fishermen are seeking out.
More Facts About Ghost Sharks
- The term “chimera” is famously used to describe a mythological creature.
- They belong to an ancient group of fish that diverged from sharks over 400 million years ago.
- They are also sometimes referred to as “rat fish” or “rabbit fish.”
- : Their lateral line system allows them to detect subtle water movements, crucial for hunting in the dark.
- They can be rarely seen by humans due to their deep-sea habitat, making them mysterious creatures of the ocean depths.
- There is a venomous spine in front of their dorsal fin for defense against predators.
FAQs
Why are they called ghost sharks?
They’re called ghost sharks due to their coloring and general appearance. They resemble sharks in some ways but aren’t sharks. The shape of their heads is one of the major reasons they’ve been given the common name “ghost shark.”
Are ghost sharks real?
Yes, ghost sharks are real. They live in almost all the world’s oceans and prefer, generally, to live at depths of around 8,000 feet.
Can you have a ghost shark as a pet?
No. You can’t keep a ghost shark as a pet. They require a very specific environment that is very difficult to produce within someone’s home.
How do ghost sharks hunt?
Ghost sharks hunt using their keen sense of smell and specialized lateral line system, which detects vibrations and movements in the water. This helps them locate their prey in dark depths.
