- Although the flesh of the almaco jack is considered quality table fare, the species has been associated with ciguatera poisoning, a seldom fatal stomach irritation.
- The almaco jack is susceptible to tapeworm parasites in the caudal peduncle area, but the meat can be eaten safely if affected portions are cut away.
Bonnethead shark (Sphyrna)
Bonnethead sharks are the smallest constituent of the hammerhead family of sharks and, as such, have eyes located at the far ends of extended lobes of the head, which is characteristic of this group. This species is especially recognizable because the head is smooth and widens into a spade-like semi-circular shape that is much more curved than that of other hammerheads. In fact, bonnetheads are often misidentified as hammerheads.
Bonnethead sharks have a gray to gray-brown color on the top and sides. Occasionally this color will have a greenish tint to it. From the sides, the color fades to a lighter, gray to white color on the bottom. The body is relatively compact and constructed of cartilage rather than bone. They have no air bladders and have specialized intestines that contain very strong digestive chemicals.
The distinctive head is compressed in length and expanded in width with a clear curved shape. When bonnethead sharks swim, the head rolls from side to side. The eyes are located at the far side of the head, which increases their field of vision. The mouth has two sets of teeth. One set of teeth is very sharp and helps cut up soft prey, the other set is large and powerful which helps break hard food items. Like all sharks, they have additional rows of teeth that rotate into place when a tooth is lost or worn. The first dorsal fin is high and begins just behind the base of the pectoral fins. The second dorsal fin has a poorly developed rear lobe and is higher and shorter than the anal fin. The pectoral fins are short.
Bonnethead sharks have a diverse diet that focuses on smaller prey. Their favored foods are hard-shelled crustaceans and mollusks, particularly blue crabs. They also have a taste for shrimp, octopus and small fish. On occasion they will eat sea grasses.
This species is well adapted for feeding. They have well developed sensory and nervous systems. The eyes are very sensitive to light and shadows, which allows them to see well in areas of low light. They also have an exceptional sense of smell. Finally, their lateral line senses even the smallest vibrations, which can alert them to possible prey hundreds of feet away. This combination of senses makes them very adept feeders. They have great agility as well, which assists them in attacking prey. Generally, when they are preparing to feed, they will swim slowly within range and then accelerate rapidly to attack.
Limited to the warm, subtropical waters of the Western Hemisphere, bonnethead sharks are typically found between 41 degrees north and 34 degrees south latitude, in the western Atlantic and eastern Pacific Oceans. In the Atlantic, bonnetheads can be located from North Carolina to Georgia, Florida and the Gulf of Mexico, south through the Caribbean Sea around Cuba and the Bahamas and continuing south to Brazil and Argentina. On rare occasions they will be found as far east as Bermuda and as far north as Rhode Island. In the Pacific, they occupy an area running from southern California to Ecuador and Peru.
Within their range, these sharks confine themselves to warm coastal waters and are generally an inshore species that inhabit reefs, sandy bottoms, areas of surf, bays and some river estuaries. As an active tropical shark, they travel great distances during their seasonal migrations and inhabit water as deep as 260 feet. They spend most of their lives at depths of 30 to 80 feet. They prefer water temperatures above 70 F and can tolerate much warmer temperatures. Their seasonal migrations are related to changes in water temperatures with migrations to warmer water in winter and cooler water in summer. As a result they are found closer to the equator in winter and at higher latitudes in the summer.
Bonnetheads seldom travel alone and are usually found in small schools of 5 to 15 members. Occasionally, they will be seen near the surface in groups of 100 or more. There have been reports of migrating schools numbering in the hundreds and thousands. They are not a territorial species, though they appear to have a hierarchy within the species. They also tend to group by gender, especially around spawning time.
- Bonnethead sharks excrete a unique body fluid for communication. Though little is currently known about this fluid, it is known that it helps them know when others are nearby.
- Bonnetheads must remain in constant motion to survive. This is necessary to force water through their gills so they can obtain oxygen. In addition, lack of motion causes them to sink.
- There has only been one confirmed bonnethead attack on a human.