Porbeagle shark
The porbeagle shark, a member of the Lamnidae family, is a swift swimmer often referred to as the mackerel shark. It features a distinctive dark bluish-grey coloration on its upper body with a white underbelly. Measuring between 65 and 144 inches (165 to 365 cm) in length, with an average size of about 10 feet (3 meters), these sharks can weigh up to 506 pounds (230 kg). Porbeagles possess sharp, slender teeth suited for their diet, which primarily consists of prey like mackerel, pilchards, and other fish that swim in large schools, as well as bottom-dwelling species such as cod and flounder.
Reproduction occurs from September to November, with females giving live birth to an average of four young after a gestation period of 8 to 9 months, a process known as ovoviviparity. Porbeagles prefer temperate waters, often avoiding severe temperature shifts by migrating to deeper, warmer areas during winter. They typically inhabit depths of up to 80 fathoms (480 feet or approximately 144 meters) and have a lifespan ranging from 25 to 45 years, with many living around 30 years. This species showcases significant adaptations for life in cooler ocean habitats.
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Porbeagle shark
The porbeagle is a swift swimmer. It is also called the mackerel shark and shares some physical characteristics with the shortfin mako shark (Isurus oxyrinchus), the white shark (Carcharodon carcharias), and the salmon shark (Lamna ditropis).
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Lamniformes
Family: Lamnidae
Genus: Lamna
Species: Nasus
The skin of the porbeagle is dark bluish grey above and white below. This thick, heavy-set fish has many fins which help it move through the water. The porbeagle has a forked caudal, or tail, fin. The upper lobe of this forked fin is much longer than the bottom lobe. Beneath the lower lobe of the porbeagle's caudal fin is a small keel. Along the porbeagle's back is a large dorsal, or back, fin. This fin is above the porbeagle's pectoral, or side, fins. The porbeagle's second dorsal fin is above its dusky-grey anal, or belly, fin.
Although the porbeagle is a large fish, it is not the largest member of the Laminidae family. Porbeagles measure between 65 and 144 inches (165 to 365 centimeters), but the average length is closer to 10 feet (a little more than three meters). The porbeagle shark weighs up to 506 pounds (230 kilograms), but the average shark weighs 300 pounds (135 kilograms). The porbeagle shark is different from other similar species in its sharp, slender teeth.
The diet of these sharks includes mackerel, pilchards, dogfish, and herrings. These fish are easy prey for the porbeagle because they swim in large schools. The porbeagle also preys on bottom-dwelling fish such as cod, hake, and flounder but does not eat marine mammals.
The porbeagle sharks breed from September to November. The female gives birth to an average of 4 live young after developing the eggs inside of her for 8 to 9 months. This process of reproduction is known as ovoviviparity.
The porbeagle is most comfortable in the temperate zone, where there is no dramatic change in water temperatures between seasons. This shark has been known to enter cool waters, but during winter, it avoids severe drops in ocean temperatures by moving into warmer, deeper waters. The porbeagle is not as strong a swimmer as other sharks of the Atlantic Ocean and inhabits deeper waters. It has been reported at depths of 80 fathoms or 480 feet (about 144 meters).
The lifespan of porbeagle sharks in the wild is between 25 and 45 years, though most live 30 years.
Bibliography
Edmunds, John, and Richard Meredith. "Lamna Nasus." Animal Diversity Web, animaldiversity.org/accounts/Lamna‗nasus. Accessed 15 Apr. 2024.
"Porbeagle Shark." The Wildlife Trusts, www.wildlifetrusts.org/wildlife-explorer/marine/fish-including-sharks-skates-and-rays/porbeagle-shark. Accessed 15 Apr. 2024.