Aggregation-forming
Guides
Gyrinus gehringi
whirligig beetle
Gyrinus gehringi is a species of whirligig beetle in the family Gyrinidae, described by Chamberlain in 1929. The species is known from North America, with records from Canada including New Brunswick, Newfoundland, and Nova Scotia. Whirligig beetles in this genus are small to medium-sized aquatic beetles that live on the water surface, where they form conspicuous aggregations and exhibit rapid, erratic swimming behavior.
Gyrinus plicifer
whirligig beetle
Gyrinus plicifer is a species of whirligig beetle in the family Gyrinidae. It occurs in North America, with records from British Columbia, Canada. Like other members of the genus, it inhabits the surface of freshwater bodies where it forms aggregations. The species was described by LeConte in 1852.
Pleuroncodes planipes
pelagic red crab, tuna crab, squat lobster, langostilla, benthic anomuran red crab
Pleuroncodes planipes is a pelagic and benthic anomuran red crab distributed across the eastern Pacific Ocean, from California to Panama. The species exhibits a complex life cycle with both pelagic and benthic phases: larvae and small individuals occupy open waters, while larger adults become exclusively benthic. It forms exceptionally dense aggregations on seamounts, with recorded densities up to 78 crabs/m² at depths of 355–385 m. The species tolerates hypoxic conditions (0.04 ml/l oxygen) and serves as a major prey item for large pelagic predators including yellowfin and skipjack tuna.
Publilia erecta
Publilia erecta is a treehopper species in the family Membracidae, tribe Polyglyptini. Like other members of its genus, it is known for forming aggregations on host plants and engaging in mutualistic relationships with ants. The species has been documented in the southwestern United States and Mexico. Treehoppers in this genus are notable for their complex social behaviors and ant-tended aggregations, though specific details for P. erecta itself are limited in published literature.