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Information about Skate Fish

[Phylum: Chordata] [Class: Chondrichthyes] [Superorder: Batoidea] [Order: Rajiformes]

Skates are cartilaginous fishes that belong to the family Rajidae. Even though they look like rays, there are several notable features and traits that set them apart.

This section contains fun facts and information about skate wing fish, including where they live, what they eat, and how they reproduce.

Sea Skates Habitat and Geographical Range

You can find skate fishes living in most foreshores (intertidal zones) all around the world.

The majority fall under the Order Rajiformes. But, the classification has three described families, that being:

The diverse habitats of sea skates include tropical environments, outer continental shelves, and some polar waters of the Arctic Ocean. They can survive at shallow coastlines, as well as at depths nearing 3,000 metres below sea level (9,850 feet).

Even so, it's more common to find many of its close relatives, the stingray species, inhabiting the shallow regions where the temperature of the water is 'naturally' warmer.

Fun Fact: There is a single estuarine species, known locally as the Port Davey skate (Zearaja maugeana), that is endemic to Tasmania, Australia. But, in the main, skate fish do not live in brackish or freshwater ecosystems.

Unique Characteristics of Skates

Besides the sea skate, Chondrichthyes is a classification of aquatic vertebrates that also includes sharks, stingrays, and chimaera fish (sometimes called ghost sharks).

In essence, it means they are all cartilaginous fishes that lack bones. Thus, marine biologists are unable to recover accurate fossil evidence about skate species.

Here's the thing:

By and large, skate wing fish have a flat body that is usually rounded (diamond-shaped, circular, or rhomboidal) in its appearance.

The usual body colouring for skates is varying tones of brown, which may be patterned or solid. The skin is scaly, often with thornlike, non venomous spines protruding from the upper surface.

Large pectoral fins extend from the snout all the way down to the base of a slender tail. Like most batoid fishes, a skate's rostral cartilage (protruding nose), and mouth and gill slits located on the underside, are common features of this particular genus.

How Big are Skate Fish?

Some of the longest sea skates can grow two and a half metres in length (8 feet). Plus, it's not uncommon for the biggest skate of all (Beringraja binoculata) to weigh 90 kilograms (200 pounds) at full maturity.

Zoologists believe there are around two hundred (200) different species of skates scattered all around the world, including:

There are few specimens in the animal Kingdom that have a bigger liver than the skate fish - accounting for 25% of its body mass. Having a huge liver means most skates are able to stay near the ocean floor for long periods of time.

Pro Tip: Research suggests that most skates (Rajidae) and ray fish have good vision - especially when the light is dull or faint. They may also be capable of recognising different colours underwater.

What Do Skate Fish Eat?

Being a typical carnivore, and spending most of the time colonising the ocean floor, the overwhelming majority of skates feed on active bottom dwelling sea creatures by trapping them from above, especially:

Interesting Fact: Skates and the electric ray are the only chondrichthyans with electric organs in the tail (used for communication rather than hunting). Plus, the skate is the only electrogenic fish that has paired electric organs running lengthwise through the tail.

Sea Skate Reproduction Process

Unlike most of the ray fish families and manta rays, which give birth to live offspring, skates lay eggs. The leathery case that protects the eggs, known as the mermaid's purse, is ovoid in shape and measures around 125 mm long (5 inches).

For the most part, the age of sexual maturity for sea skates is ten (10) years. Following a successful courtship, the gestation period of up to forty eggs can last up to twelve (12) months in some species.

Fun Fact: The egg capsule usually contains only one embryo. But, there can be up to seven (7) embryos for some species, such as the mottled skate (Beringraja pulchra).

Threats and Predators

As a matter of fact, several different species of skate fish (e.g. common skates) are popular to eat in restaurants in northwestern Europe and other countries based around the Mediterranean Sea.

Despite having a lifespan of up to one hundred (100) years, the species has become vulnerable to abrupt declines in population. Typical reasons for this include:

Note: The International Union for Conservation of Nature lists the conservation status of skate fish in a range from Least Concern (LC) to Critically Endangered (CE).

Related Information and Help Guides

Note: The short video [4:13 seconds] presented by 'Deep Marine Scenes' contains facts about skate fish and the key differences between skates vs. stingrays.

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