Sharksonline's Blog

Spinner shark

Posted on: May 2, 2010

Above the Spinner shark

1. People mistake the black tip shark for the spinner shark. They live in the western Atlantic ocean and the eastern Atlantic. And pass throw the Indian Ocean. They can be found at a depth of 100 m (330 ft) or at the surface at less than 30 m (100 ft) deep. It prefers shallow water. In the spring and the summer they are found in warm inshore water. and in the winter they move south into deeper water.

2. The average spinner shark is 2 m (6.4 ft) long and weighs 56 kg (123 lbs). The maximum known length and weight of 3 m (10 ft) and 90 kg (198 lbs). Indo-Pacific sharks are generally larger than those from the northwest Atlantic. This species has a slim body. The eyes are small and circular. The tooth rows number 15–18 in each half of the upper jaw and 14–17 in each half of the lower jaw. The teeth have long and narrow central cusps and are finely serrated in the upper jaw and smooth in the lower jaw. The five pairs of gill slits are long. The first dorsal fin is relatively small.  There is no ridge between the first and second dorsal fins. The pectoral fins are moderately short, narrow, and falcate (sickle-shaped). Young individuals have no black tip on its fin.
And on one of the fin it has a black band on both sides of the fin. But not all over the fin.

3. The spinner shark is a fast swimmer that sometimes forms large schools. Young individuals prefer cooler water temperatures than adults. Off South Africa, females are found close to shore year-round while males only appear during the summer. Smaller spinner sharks may be preyed upon by larger sharks.

4. Spinner sharks feed on small bony fishes including tenpounders, sardines, herring, anchovies, sea catfish, lizardfish, mullets, bluefish, tunas, bonito, croakers, jacks, mojarras, and tongue-soles. They have also been known to eat stingrays, cuttlefish, squid, and octopus.

5. The spinner shark is viviparous. Adult females have a single functional ovary and two functional uteruses each uterus is divided into compartments one for each embryo. The embryos are initially sustained by a yolk sac. When the embryo grows to around 19 cm (7.5 in) long the supply of yolk has been exhausted and the empty yolk sac develops into a placental connection through which the mother provides nutrients for the remainder of gestation. This species has the smallest ova relative to the fully developed embryo of any viviparous shark known. Females give birth to 3–20 (usually 7–11) pups every other year after a gestation period of 11–15 months. Mating occurs from early spring to summer and parturition in August off North Africa from April to May off South Africa, and from March to April in the northwestern Atlantic. Young are birthed in coastal nursery areas such as bays, beaches and high-salinity estuaries in water deeper than 5 m (20 ft).The length at birth is 66–77 cm (26–30 in) in the northwestern Atlantic, 61–69 cm (24–27 in) off Tunisia and 60 cm (24 in) off South Africa. Males mature at 1.8 m (5.9 ft) and females at 2.1 m (6.9 ft). Spinner sharks generally do not reproduce until they are 12–14 years old. The maximum lifespan has been estimated at 15–20 years or more.

6. As of 2008 there has been 16 unprovoked attacks and 1 provoked attack attributable to the spinner shark and none of them fatal.

All of this info is from http://en.wikipedia.org/wiki/Spinner_shark

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: