Largetooth sawfish

800px-2009_Pristis_microdon2

Profile

The largetooth sawfish is a large fish living near coasts around the world. Their range includes southern North America, Central America, northern South America, western Europe and Africa, as well as several islands in the Pacific, including Australia. As with the bull shark, the largetooth sawfish is euryhaline, meaning it can survive easily in both salt-water and fresh-water. They have in fact been spotted as far as two hundred and fifty miles (400 km) up-stream away from the sea. Although they can live equally well in both habitats, largetooth sawfish prefer saltwater over freshwater. The edge of this animal’s saw-like nose contains fourteen to twenty-three evenly-spaced teeth on each side. As with many cartilaginous fish (skates, rays, and sharks), sawfish, which fall under the rays category, have a darker topside and a light underside. This helps them blend in with their surroundings whether they are looked at from the top or from the bottom.

Size

Largetooth sawfish are very large and can grow up to twenty-three feet long! Reports of sawfishes this long have not been confirmed, but the maximum confirmed length of 19.7 feet (6 m) is still quite long. The maximum recorded weight is about 1,322 pounds (600 kg). This is a little less than half of the weight of a Honda Civic, the most popular car in the United States.

Diet

Young largetooth sawfish will eat small fish along with crustaceans. As they grow older, their diet includes more and larger fish and fewer crustaceans. Individuals use their “saw” to rake the silt at the bottom of the river or ocean. This scares animals out, and the sawfish can then eat them. They can also thrash their saw through schools of fish in order to stun their prey, making it easier to catch. Sometimes while doing this, fish get impaled on the teeth. These unlucky individuals are scraped off onto the ground and then eaten. The thresher shark also stuns prey by thrashing, but it uses a different body part.

Status

Historically, the largetooth sawfish was a wide-ranging species with a large population. Currently the population has diminished very much, and northern Australia is now one of the few places where these animals are common. The IUCN Redlist states that these animals are critically endangered throughout most of their range. In Australia, the largetooth swordfish is “just” vulnerable (two steps more common than critically endangered).

Threats

Largetooth sawfish have very few predators. One known predator of these animals is the american crocodile. The main threats of these fish are habitat loss and fishing by humans. Their saw-like snout or rostrum (Last weeks animal had a rostrum too! Read about it here!) often gets entangles in fishing nets. Even if the fishermen do not mean to catch the sawfish, some can die from this anyway. Some fisheries have a code of conduct to release any of these animals that have been accidentally caught. Adult sawfish are hard to handle, however, and some individuals cannot be released if accidentally caught. Both the fins of these animals and their rostrum are highly valued, and some people will purposely fish for largetooth sawfish to sell these body parts. Such fishing is illegal, and fishermen are given guidelines on how to safely release any swordfish they catch. It is illegal to kill them or even just keep the rostrum as a trophy.

Habitat loss is a threat to the young swordfish that live in freshwater regions. People have built dams in rivers, and these can be hindrances to sawfish migration. Here is a video about conservation of these animals.

Reproduction

Not much is known about the reproduction of the largetooth sawfish, but their gestation period is known to be around five months. While mating, the males grasp the females with special “graspers”. Only males have these appendages. All sawfishes are born live after the eggs hatch inside their mother. Before the young are born, their rostrum is covered by a gel. This protects the mother from injury during birth. Young largetooth sawfishes are born in freshwater, and females give birth every other year. Each female gives birth to between four and ten young each time. As the young mature, they migrate to the ocean where they normally stay close to the shallows. These amazing fish can live for up to thirty years.

 

Don’t forget to  scroll down and comment your guess about what the next animal is!

OLYMPUS DIGITAL CAMERA

Sources:

Photo credits:

  • Largetooth sawfish – J. Patrick Fischer
  • Mystery animal – Serban Proches

 

One Response

  1. Sharon Madson
    Sharon Madson at |

    The sawfish is pretty from the underside. I liked the video, too. Thank you, I learned something new, as always from your post today.

Comments are closed.

%d bloggers like this: