Alosa "oligorakered." The multirakered are primarily plankton feeders, the oligorakered have large rakers and are predators, and the medium-rakered generally consume a mixed diet. Most current species of the genus "Alosa" in North America can be found in Florida, whereas the distribution of most of them is broader. Morphology is notoriously liable to adapt to changing food availability in these fish. Several taxa seem to have evolved quite recently, making molecular analyses difficult. In addition, hybridization may be a factor in shad phylogeny. Nonetheless, some trends are emerging. The North American species except the American shad "A. sapidissima" can probably be
Rockhead (fish) Rockhead (fish) The rockhead ("Bothragonus swanii"), also known as the deep-pitted poacher or deep-pitted sea-poacher, is a fish in the poacher family, Agonidae. It was described by Franz Steindachner in 1876, originally in the genus "Hypsagonus". It is found in the eastern Pacific Ocean from Alaska to Carmel Bay, California down to depths of 18 metres. It can also inhabit the intertidal zone. Males can reach a maximum total length of 8.9 centimetres. The species epithet ""swanii"" refers to James G. Swan of Port Townsend, Washington. The rockhead spawns nearshore, during the months of January–May in the California Current region.