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Oceanic fauna of the Atlantic
JOrnitho: I'm opening this new topic because I finished the description of fish. However, I don't know which scientific name it could have. Any suggestions? Blue porpoise fish A member of the Scombridae family, the blue porpoise fish is the type species of the genus. An inhabitant of the Atlantic Ocean, this species evolved to fill the niche left behind by dolphins and porpoises when they went extinct during the transition between the Holocene and the Neocene. All the members of this genus have the habit of constantly jumping from the water. The blue porpoise fish have 120 cm of length. They have an elongate, fusiform body with a long, pointed snout. The eyes are large and covered by an adipose eyelid, while the teeth are small, sharp, and conical. Scales are also small, with the exceptions of those immediately posterior to the head and around the pectoral fins. These small scales give the fish a velvet-like feel. The two dorsal fins are large and bright yellow, being spaced far apart. The second dorsal fin is typically followed by 4 dorsal finlets. Its body is blue dorsally, while the rest is silvery-white and has darker splotches. When feeding on larger prey, schools tend to break down into shoals and individuals find food on their own. When consuming plankton, however, blue porpoise fish form tight aggregations, open their mouths as wide as possible, and extend their operculums, swimming in a tightly-packed school that acts like a series of miniature tow nets. Spaced only about the diameter of a single fish's mouth apart, this formation greatly reduces the ability of plankton to evade capture, as a plankton darting out of the way of one fish is likely to end up in the jaws of another. These fishes are followed by seabirds, which will use them to locate prey in similar way to how it happened with cetaceans in the Holocene. Reproduction in the blue porpoise fish is oviparous. Spawning occurs day or night in the spring and summer months, primarily within 52 km of shore, though it can occur as far out as 130 km. A single female can spawn as many as 420,000 eggs in a spawning season. Eggs mature in batches over the course of a week and are pelagic once released, remaining within 15–25 of the surface. Time to hatching is dependent on the water temperature, and ranges from 2 days at 21 °C to 8 days at 10 °C. Most eggs are spawned in waters 12 °C in temperature, and as such the majority of eggs hatch in about a week. Eggs are anywhere from 1.0–1.3 mm in size, trending towards smaller as the spawning season goes on. Larvae undergo three developmental stages: the yolk sac stage, the larval stage, and the post-larval stage. Larvae are 3 mm when they hatch and feed on the yolk sac for about 5 days. During the larval stage, which lasts about a month, larvae grow to 10 mm in length. They are largely incapable of swimming, instead floating with the current. During the post-larval stage, which occurs over the next 40 days and during which the fish reaches 50 mm in length, it swims to the surface at night and down to deeper waters during the day. At the end of the post-larval stage, juveniles resemble an adult mackerel in all but size. Schooling behavior occurs around this time. Sexual maturity is reached at around 2 years of age, though some fish may reproduce a season earlier or a season later. Though some fish are sexually mature at 39 cm in length, even by 45 cm only about half of females will be ready to reproduce. At 53 cm, most fishes are capable of reproduction. A blue porpoise fish can live for up to 21 years.
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