The 'Stinging Bush Hydroid' (Macrorhynchia philippina) is a large (50–400 mm) conspicuous, feather-like hydroid with a circum-tropical distribution. It was described from the Philippines, and is found from South Africa to Japan, Hawaii, Australia, and Polynesia. In the Western Atlantic, they range from Brazil to North Carolina and Bermuda. In the Eastern Atlantic, there are early records from the Cape Verde Islands (1907) and Guinea-Bissau (1931), but more recent records from Madeira (1976) and the Canary Islands (2014) where it considered a recent invader. Since 2014 there are also multiple recent records from Portugal, and one from Brittany (2021). In the Mediterranean, it was found in Turkey and Lebanon by 2005, where it is considered to be introduced via the Suez Canal. There are recent records from Corsica (2020) and Antibes (2018), France, in the Western Mediterranean.
In The Eastern Pacific, Macrorhynchia philippina was first collected in the Galapagos Islands in 1931, and by 1948, was found from Gull Island in the California Channel Islands* to Peru. Calder et al. (2022) consider M. philippina to be a likely introduction to the Eastern Pacific, from the Indo-Pacific (more likely) or the Atlantic, based on the genetic similarity of worldwide populations, the limited dispersal of its non-buoyant medusoids, and its occurrence on artificial structures and vessel hulls. In 2018, one specimen was identified from fouling plates on Cocos Island, Costa Rica. In the Canary Islands, and the Eastern Mediterranean (Turkey and Lebanon), invasions of this species raised concern because of its local abundance and powerful venomous sting.
*We have not found recent California records.