Shark Ray

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Shark Ray

Synopsis

Shark rays inhabit shallow coastal waters or waters around coral reefs in the Pacific. Their range includes East Africa, Papua New Guinea, Indonesia, Japan and New South Wales. They feed mainly on mollusks and crustaceans. They live to be around seven years old in protected areas, but their average lifespan in other areas is unknown.

Content List

  1. Scientific & Common Names
  2. Characteristics
    1. Breeding
    2. Behavior
  3. History
  4. Present Status
  5. References


Scientific & Common Names

Kingdom - Animalia Phylum - Chordata Class - Chondricthyes Order - Rajiformes Family - Rhinidae Genus - Rhina Species - R. ancylostoma Common Names - Shark Ray, Bowmouth Guitarfish, Mud Skate, Shortnose Mud Skate, Bow-mouthed Angel Fish, Bow-mouthed Angel Shark


Characteristics

Shark rays have gray or bluish upper bodies with small white markings, white bellies and dark gray bars on their face. They have wide, flat heads with triangular fins on either side and a narrower, shark-like body. Shark rays also have spiked ridges above their eyes, on the backs of their necks and on their pectoral fins, which protect them from predators. Adults measure up to 8 feet long and can weigh up to 297 pounds, although most do not grow this large.


Breeding

Fertilized eggs remain in female shark rays’ bodies and receive nourishment from the yolk and uterine milk. They hatch inside the mother’s body and are born live, measuring around 18 inches in length. Shark rays typically give birth to four or five pups at a time. Once the pups are born, they leave their mother and live on their own.


Behavior

Shark rays typically feed at night and are relatively inactive during the day. They find prey by using their sense of smell, then they hold it down with their head while slowly pulling it in their mouth. They are able to grind up their prey with their rows of ridged teeth. Shark rays usually remain close to the bottom of the water, although they sometimes swim higher.


History

Shark rays are most closely related to guitarfishes, wedgefishes, and sawfishes, all of which are primitive rays. Some scientists believed that shark rays are the missing link that connects rays and sharks, but new molecular data casts doubt on the idea that rays are derived directly from sharks, though they are related. A description of the species appears in the 1801 publication of “Systema Ichthyologiae” written by Johann Schneider and Marcus Bloch.


Present Status

Shark rays are listed as vulnerable mainly due to a decreasing population in Indonesia. The species faces a number of threats, including unregulated commercial fishing in Southeast Asia, habitat destruction, slow reproduction rates, pollution, coral bleaching and incidental capture in fishing nets. Conservation efforts include the installation of devices in fishing nets to prevent incidental capture and a prohibition on finning in Australia.


References

    http://www.aquariumofpacific.org/onlinelearningcenter/species/bowmouth_guitarfish

    http://www.iucnredlist.org/details/full/41848/0