Chondrichthyes
(Skate Fish)
Vocabulary
Claspers-are modifications of the pelvic fins and located on the inner margin of the pelvic fins.
Ampullae of Lorenzini- are receptors that can detect weak electric fields.
Benthic Invertebrates-Animal without a backbone that lives on or below the surface of the sea bottom.
Spiracles-An external respiratory opening, esp. each of a number of pores on the body of an insect, or each of a pair of vestigial gill slits.
Prey-Hunt and kill for food.
Ampullae of Lorenzini- are receptors that can detect weak electric fields.
Benthic Invertebrates-Animal without a backbone that lives on or below the surface of the sea bottom.
Spiracles-An external respiratory opening, esp. each of a number of pores on the body of an insect, or each of a pair of vestigial gill slits.
Prey-Hunt and kill for food.
Classification
Morphology
Skates are the class of fishes whose skeleton is made of cartilage, a tough, flexible supporting tissue. Skates have gills that open to the outside, have no swim bladder and have a sandpaper rough skin covering rather than scales.
Skates (Order: Rajiformes):
Skates (Order: Rajiformes):
- Each pelvic fin is divided into two lobes.
- Tail is relatively stocky without a stinging spine.
- Tail usually has two small dorsal fins near its tip and a tiny caudal fin. Although some species lack dorsal and caudal fins.
- Bucklers (thorn-like scales) may be present along the midline of the back or tail. Enlarged scales along the side of the body (near the pectoral fin base) may also be present in some species.
- Males have rows of enlarged scales near the eyes and wingtips (termed 'malar' and 'alar' spines, respectively).
- Skates lay egg cases (via oviparity).
Biology
What adaptations do skates have to enable them to have flat bodies?
The dorso-ventrally flattened bodies allow skates to glide closely over the bottom sediments in search of prey. Their eyes and spiracles are positioned on the top of the head which allows them to take in water for gill ventilation (respiration) while partially buried in the sand. The mouth is located on the underside of the animal as an adaptation for feeding on benthic invertebrates and fishes.
How long do skates live?
Rays and skates have life spans ranging up to 50 years.
Are and skates limited to marine habitats?
Yes, Skates are typically found in more saline habitats.
The dorso-ventrally flattened bodies allow skates to glide closely over the bottom sediments in search of prey. Their eyes and spiracles are positioned on the top of the head which allows them to take in water for gill ventilation (respiration) while partially buried in the sand. The mouth is located on the underside of the animal as an adaptation for feeding on benthic invertebrates and fishes.
How long do skates live?
Rays and skates have life spans ranging up to 50 years.
Are and skates limited to marine habitats?
Yes, Skates are typically found in more saline habitats.
Distribution Map
Importance
(Ecological,Economical)
Skates are, fish closely related to sharks. Like sharks, skates have skeletons of cartilage rather than bone. Most skates have bodies that are flattened from top to bottom. Their large pectoral fins, often called wings, are attached to the head. Skates live in cold seas. There are about 100 species of skates.
Skates have flat bodies and large pectoral fins attached to the head. Skates range in length from a few inches to about 8 feet (2.4 m). Most, however, are less than 2 feet (60 cm) long. Skates are usually brown or gray above, often with various markings. They are whitish below, blending in well with their environment.
Skates live on the bottom of the waters they inhabit. Skates are sluggish animals that either lie on the bottom or slowly cruise, looking for the clams, snails, shrimp, and other small animals that they eat.
The mouth in almost all skates is on the underside of the body. Skates take in water through openings, called spiracles, at the top of the head. The water is transferred to the gills, on the underside of the head.
The skin of skates is generally covered with numerous scales, but some skates have smooth skin. Skates do not have barbed tails, but some have organs along the sides of the tail that can produce an electric shock. The voltage they emit is generally low.
Young skates hatch from eggs contained in leathery, protective capsules.
Skates are eaten throughout the world. They are not popular in the United States for food but are used to make fertilizer and fish meal. The pectoral fins of some species are used to make imitation scallops in the United States.
Skates have flat bodies and large pectoral fins attached to the head. Skates range in length from a few inches to about 8 feet (2.4 m). Most, however, are less than 2 feet (60 cm) long. Skates are usually brown or gray above, often with various markings. They are whitish below, blending in well with their environment.
Skates live on the bottom of the waters they inhabit. Skates are sluggish animals that either lie on the bottom or slowly cruise, looking for the clams, snails, shrimp, and other small animals that they eat.
The mouth in almost all skates is on the underside of the body. Skates take in water through openings, called spiracles, at the top of the head. The water is transferred to the gills, on the underside of the head.
The skin of skates is generally covered with numerous scales, but some skates have smooth skin. Skates do not have barbed tails, but some have organs along the sides of the tail that can produce an electric shock. The voltage they emit is generally low.
Young skates hatch from eggs contained in leathery, protective capsules.
Skates are eaten throughout the world. They are not popular in the United States for food but are used to make fertilizer and fish meal. The pectoral fins of some species are used to make imitation scallops in the United States.
Interesting facts on Skates
What does the skin of skates feel like?
The skin skates is similar to that of sharks. The skin feels exactly like sandpaper because it is made up of tiny teeth-like structures called placoid scales, also known as dermal denticles. These scales point towards the tail and helps to reduce friction from surrounding water when the animal swims. Because of this, if someone rubbed the skin from the head towards the tail, it would feel very smooth. In the opposite direction it feels very rough like sandpaper. Skate skin may also possess thorns in different regions of the body depending upon species. These thorns help to defend skates from predators.
Do skates have good vision?
The eyes of skates are located dorsally, on the upper surface of the animal, while the mouth is located on the underside. Based on this, it is believed that vision may play only a secondary role in prey location and feeding behaviors. It is thought that most skates have good vision especially in dim light.
How do skates detect prey?
Similar to sharks,skates have many keen senses that are geared towards helping them locate prey. Depending on the species or the environment certain senses are more or less important to them for locating their targeted prey, which is most often benthic invertebrates. Elasmobranchs use the senses of smell (chemoreception), vision, hearing, the lateral line system, and electroreception (ampullae of Lorenzini) for capturing prey. The lateral line system, which most fish possess, allows them to detect waves of pressure or mechanical disturbances in the water. The ampullae of Lorenzini are receptors that can detect weak electric fields. This sense is unique skates and their relatives. They primarily use this sense to locate cryptic prey that is buried below the bottom sediments.
How can you distinguish a male from a female skate?
Male skates (as well as sharks) have claspers while females do not. Claspers are modifications of the pelvic fins and located on the inner margin of the pelvic fins. They are used to transfer sperm to the female during mating. Females do not have claspers.
What do skates feed on?
The majority of skates feed on bottom dwelling (benthic) animals including shrimps, crabs, oysters, clams and other invertebrates.
The skin skates is similar to that of sharks. The skin feels exactly like sandpaper because it is made up of tiny teeth-like structures called placoid scales, also known as dermal denticles. These scales point towards the tail and helps to reduce friction from surrounding water when the animal swims. Because of this, if someone rubbed the skin from the head towards the tail, it would feel very smooth. In the opposite direction it feels very rough like sandpaper. Skate skin may also possess thorns in different regions of the body depending upon species. These thorns help to defend skates from predators.
Do skates have good vision?
The eyes of skates are located dorsally, on the upper surface of the animal, while the mouth is located on the underside. Based on this, it is believed that vision may play only a secondary role in prey location and feeding behaviors. It is thought that most skates have good vision especially in dim light.
How do skates detect prey?
Similar to sharks,skates have many keen senses that are geared towards helping them locate prey. Depending on the species or the environment certain senses are more or less important to them for locating their targeted prey, which is most often benthic invertebrates. Elasmobranchs use the senses of smell (chemoreception), vision, hearing, the lateral line system, and electroreception (ampullae of Lorenzini) for capturing prey. The lateral line system, which most fish possess, allows them to detect waves of pressure or mechanical disturbances in the water. The ampullae of Lorenzini are receptors that can detect weak electric fields. This sense is unique skates and their relatives. They primarily use this sense to locate cryptic prey that is buried below the bottom sediments.
How can you distinguish a male from a female skate?
Male skates (as well as sharks) have claspers while females do not. Claspers are modifications of the pelvic fins and located on the inner margin of the pelvic fins. They are used to transfer sperm to the female during mating. Females do not have claspers.
What do skates feed on?
The majority of skates feed on bottom dwelling (benthic) animals including shrimps, crabs, oysters, clams and other invertebrates.