Monday, July 6, 2009

Description

Gar are long and cylindrical with elongated mouths. Spotted gar grow to a length of 3 feet (0.9 m), weighing 8 pounds (3.6 kg). Their upper body is brown to olive, and they have silver-white sides. Head, body, and fins have olive-brown to black spots that help camouflage the fish. A broad, dark stripe is on the sides of immature fish. Their long, snout-like mouth is lined with strong, sharp teeth, and their body is covered with thick, ganoid (diamond-shaped) scales. Spotted gar may be distinguished from other Texas gar species by the dark roundish spots on the top of the head, the pectoral fins and on the pelvic fins.
Life History
Gar move slowly unless trying to catch food, which it grabs in its jaws in a quick sideways lunge. They often bask near the water's surface on warm days. Fry feed primarily on insect larvae and tiny crustaceans, but fish appear on the diet of young gar very early. Prey is usually swallowed headfirst. Spotted gar are eaten by larger fish, alligators, herons, and cottonmouth snakes.

The long-lived gar has a life span up to 18 years. Males mature in two to three years. Females mature when three to four years old. They spawn in shallow water with low flow and heavy vegetation. Several males court a single larger female at the same time. Spawning season is from April to May. The number of eggs varies greatly, but up to about 20,000 green, adhesive eggs are attached to aquatic plants. Fry hatch after 10 to 14 days. Young gar have specialized pads on their upper jaws that allow them to adhere to vegetation. They remain attached to plants until they are about 0.75 inches (2cm) long. The pad is lost when last of the yolk sac is absorbed.

Gar have a specialized swim bladder which allows them to gulp air and live in the poorly oxygenated back waters of Texas' streams, swamps and lakes. Lepisosteus is Greek and means "bony scale", referring to the large ganoid scales. Oculatus means "provided with eyes" in Latin and refers to the dark spots on head, body, and fins. The common name, gar, is rooted in the Anglo-Saxon language and means "spear." The roe (or egg mass) is highly toxic to humans, animals, and birds.
Habitat
Spotted gar prefer clear, quiet, vegetated waters of streams, swamps and lakes. They sometimes enter brackish waters along the Gulf Coast.
Distribution
Spotted gar are very widespread, and can be found from central Texas east into western Florida. Their territory extends north through the Mississippi River drainage into Illinois, the lower Ohio River, and the Lake Erie drainage.
Other
The spotted gar is one of three gar species native to Texas. They are primitive fish and date back to the Cretaceous period, some 65 to 100 million years ago. The ancestors of spotted gar swam with the dinosaurs! A large gar can eat a lot of fish, including catfish, causing them to compete with some anglers. Because of the competition and because many people think gar are difficult to clean, gar are sometimes called a "trash" fish. This term may not be warranted when you consider that spotted gar, like all native species, have an important role to play in their ecosystem.

Common Names: Spotted ratfish.
Latin Name: Hydrolagus colliei
Family: chimaeridae
Identification: Broad, flat, duckbill shaped snout containing incisor shaped teeth. Large eyes. Prominent, venomous spine at leading edge of dorsal fin. Tapering tail constitutes almost half overall length. Coloration brown or grey with white spots. Skin smooth and scaleless. Can give off an iridescent, silvery sheen. Triangular pectoral fins well developed. Fins grey or dark.
Size: up to 97cm in length.
Habitat: Sand and mud bottoms and sometimes rocky reefs. from 0 to 3000ft.
Abundance and distribution: From Southeastern Alaska to Central Baja. Common from British Columbia to Northern California.
Behavior: Swims slowly across sand in search of prey. Crushes clams, crabs, and shrimp etc. in forward facing "incisors". Food located primarily by smell. Uses its pectoral fins for locomotion.
Reproduction: Oviparous. After elaborate courtship rituals the female lays a spoon shaped egg capsule. The extrusion process can last 18 to 30 hours and the capsule is retained on thin tendrils for between four to six days until finally caught on the seabed or planted in the sand.
Reaction to divers: During the day moves slowly. With patience it is possible to get quite close. Although able to inflict a mildly toxic wound, it is not aggressive and prefers to maintain a safe distance.
Diving logistics: In British Columbia this Chimaera is quite easy to find. One very nice dive is off of the Ogden Point breakwater. This is a 1km long jetty that runs away from shore into about 120ft of water. From about 2/3rds of the way along, the water is deep enough to support ratfish. To find them simply take a compass reading away from the breakwater and head directly out into the sand. The terrain is fairly featureless and unappealing but supports a reasonable number of ratfish. I have seen about 10 ratfish within a few minutes here at about 80ft in November. Ogden Point Breakwater has a full service dive shop at its base and offers air and nitrox fills. The walk out can be a bit challenging in full gear. The breakwater itself offers excellent shore diving with opportunities to see wolf eels and giant pacific octopuses. Spiny dogfish (Squalus acanthias) may be encountered at the far end of the breakwater but this area is deep and current swept.

Wednesday, June 24, 2009

Description & Behavior

The balloonfish, Diodon holocanthus (Linnaeus, 1758), aka balloon porcupinefish, blotched porcupine fish, blotched porcupine, brown porcupine fish, fine-spotted porcupinefish, freckled porcupinefish, freckled porcupinefish, hedgehog fish, long-spine porcupinefish, porcupine, porcupinefish, spiny balloonfish, and spiny puffer, is known for its large eyes, spines and it's ability to swell like a balloon when attacked. This comical species reaches between 20-35 cm, and reaches a maximum of 50 cm. There are a total of 13-15 dorsal and anal soft rays. Juveniles have spots on the ventral side, adults have dark blotches and spots on the dorsal side. There are 14-16 spines between the snout and dorsal fin. A large brown bar is found above and below each eye; and a broad transverse brown bar on occipital region, or upper surface of the back of the head.
The body of the balloonfish is covered in long, sharp spines that extend when the fish inflates by taking in water. All members of the Family Diodontidae are capable of inflation, and may also change in color when threatened.
World Range & Habitat
Circumtropical in distribution. These fish are found in the Western Atlantic from Florida, USA to the Bahamas and Brazil, in the Eastern Atlantic around 30°N-23°S, and in South Africa. In the Eastern Pacific from Hawaii to Pitcairn and the Easter Islands, and from southern California, US to Colombia and the Gal├ípagos Islands. They are reef fish with a depth range of 2-100 m.
Feeding Behavior (Ecology)
Balloonfish are nocturnal predators, generally hiding in crevices in the reef during the day. The teeth are fused forming a strong, beak-like mouth for consuming snails, sea urchins, and hermit crabs. These fish are relatively poor swimmers. Juveniles are consumed by pelagic predatory fishes such as tuna and dolphins. Adults fall prey to sharks.

Life History

Reproduces via dioecism (sexes are separate), fertilization is external with a spawning frequency of one clear seasonal peak per year.
The balloonfish has a pelagic life stage. Spawning occurs after males slowly push females to the surface. The eggs are buoyant, hatching after approximately 4 days. The larvae are well developed with a functional mouth, eyes, and a swim bladder. They are predominately yellow with scattered red spots, and are covered with a thin shell until they are about 10 days old, after which the shell is lost and the spines begin to form. Approximately 3 weeks after hatching, the fins and fin rays are present and the teeth are formed. As juveniles, they develop their olive to brown color with dark spots appearing on the ventral side that serve as camouflage for juveniles floating in Sargassum weed. The spotting is retained until the juveniles move inshore and become adults.

 

Photoshop Tutorial | Proxy Server | The Green Planet | pandhito band | Your Dentist