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parc distributors
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Squalus Acanthias; spiny dogfish
DistributionThe distribution of the real spiny dogfish is limited since these animals generally prefer a water temperature ranging between 7 and 15 degrees. Nevertheless, they may well have the largest population of any given shark species. The annual catch along the Massachusetts (USA) coast alone used to amount to approximately 27,000 tons. Age The age limit of these animals is still very speculative. Literature sources cite values of 30 and sometimes even a 100 years. Feeding Much knowledge on the biology of the spiny dogfish is only fragmentary. In 1998, for example, it was discovered that the animals have two separate feeding methods: On the one hand they suck in their food by quickly lowering the lower jaw to produce a kind of suction, and on the other hand some potential prey is rammed before being eaten. Their food palette appears to consist of school fish as well as spineless animals such as crabs or mussels. Reproduction Spiny dogfish reproduce in a way which makes them extremely vulnerable to fishing methods. The age at which they reach sexual maturity is very difficult to determine. Some observations point to 10 to 20 and even 30 years. Such fluctuations may indicate that their habitats are marked by differences. External factors such as water temperature and food supplies may influence sexual maturity as well as the size of the litter which may range between one and twenty animals. Generally, they have an above-average pregnancy period of 18-24 months which is longer compared to other shark species. Usually spiny dogfish do not exceed a length of approximately 120 cm, whereby sexual maturity is usually reached by males measuring 60 to 70 cm and females measuring 70 to 100 cm. Length at birth may be around 22 to 23 cm. If these factors are integrated - late sexual maturity with small litter sizes and a long pregnancy time - it is by no means surprising that excessive fishing has a destructive influence on spiny dogfish populations. Their "slow" reproduction rate does not allow easy restoral of its unstable populations. Enemies Their numbers are negatively influenced both by fishing and their relatively small size, which makes them easy prey for other sharks, sea lions and swordfish. Behavior Spiny dogfish often live in swarms consisting of thousands of animals. These swarms are formed in order to hunt together, but also as protection against enemies. Certain swarms consist of pregnant females in search of their nesting grounds, which include the San Francisco Bay. Females and males usually live in separate swarms. Mixed groups are rare. Males prefer flatter regions while females only return to flat coastal areas to bear their young. Spiny dogfish undertake long migrations, influenced partly by the availability of food and partly by water temperatures, but their migration path has not yet been studied sufficiently. One tagged animal was found to have migrated 6,500 km, but the reasons behind this behavior remain purely speculative.
Somniosus Microcephalus; sleeper shark
Somniosus microcephalus, is also called the sleeper shark and the gurry shark. This large, slow-swimming shark has glow-in-the-dark eyes. It lives in very deep waters of the North Atlantic Ocean. It lives at depths down to 1,800 feet (550 m) in very cold water (36 to 45°F=2 to 7°C). These sharks gather in large numbers in shallow Arctic waters (up to 80° North) during the winter but migrate back to deep waters during the summer. Eskimo hunters traditionally used this shark's skin for boots and its teeth for knives. Anatomy: The Greenland shark is up to 21 feet (6.5 m) long. This grayish-brown shark has a short snout and small fins. Bioluminescent (glowing) copepods attach to the Greenland shark's corneas (a part of the eyes). This may attract curious prey to the shark's head! The shark's upper teeth are long and sharp; the lower teeth are flatter, more closely-set (and also sharp). Diet: The Greenland shark eats fish (like salmon), dead cetaceans (whales), and pinnipeds (like seals and sea lions). Reproduction: This large shark is ovoviviparous, having litters of about 10 pups, each roughly 15 inches (38 cm) long. Classification: Kingdom Animalia, Phylum Chordata, Class Chondrichthyes, Order: Squaliformes, Family Squalidae (dogfish sharks). Chimera Monstrosa; Ratfish
They have large heads, long, thin, ratlike tails, and large, fanlike pectoral fins. In many species there is a poison spine in front of the first dorsal fin. Their slippery skins are black, gray, or silver, often with stripes or spots. The largest reach a length of about 61/2 ft (2 m). Chimaeras resemble sharks in certain fundamental respects: They have cartilage skeletons, males have claspers for internal fertilization of females, and females lay eggs encased in leathery cases. However, they resemble the bony fishes in having the upper jaw fused to the skull, the gill slits opening into a single chamber, a bony covering, or operculum, over the gill slits, and separate anal and urogenital openings. A distinctive feature of chimaeras is the presence of extra claspers in the male, one in front of each pelvic fin and a prominent one on the forehead. The function of these appendages is not known, but they are thought to play a role in courtship. |
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Research Information | History of Shark
Liver Oil | Research & Development
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The spiny dogfish is known primarily by
virtue of its largest representative, the real spiny dogfish, Squalus
acanthias. But the name "spiny dogfish" is not reserved for this one
specific species alone. It covers an entire family of spiny dogfish
including, for example, such different forms as cookie-cutter sharks. The
name "spiny" shark is actually misleading since contrary to expectations,
not all species of the group have the typical spines in front of the
dorsal fin. Although the species in this family in part look different,
they do have one thing in common: the suction holes behind the eyes and
the lack of an anal fin. Most species of spiny dogfish actually live quite
deep in the ocean. Obviously, this makes their observation in their
natural environment very difficult and much of our knowledge on this
species is thus speculative. Generally speaking, very little is known
about its biology. The best researched species is the real spiny dogfish,
Squalus acanthias, whereby here too, knowledge is mostly limited to
information relevant to fishing.
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