Orange-striped anemone - Diadumene lineata

Characteristics:
This small sea anemone has a global reach unlike any other sea anemone around the world (Hancock, Goeke and Wicksten, 2017). The orange-striped anemone (fig. 1) is a small, independently growing species of up to 2cm wide (Ma et al, 2020). While their colour can vary, they tend to be green to grey, and may or may not display their eponymous orange stripes (Smithsonian Environmental Research Centre, n.d.). They sport between 25 and 100 small tentacles, while thinner, stinging tentacles can be brought out from within (NNSS, 2022).
Orange-striped anemones can undertake multiple forms of reproduction, varying by location. In its native range, both male and female individuals exist together, allowing sexual reproduction to occur. Only recently have examples of sexual reproduction been recorded out with their native range, identified in the USA (Ma et al, 2020). In the UK, reproduction is believed to occur asexually (NNSS, 2020), a characteristic thought to contribute to the species' success in spreading around the globe (Hancock, Goeke and Wicksten, 2017). Even in its larval stage, the species can attach to substrate such as boats (Hancock, Goeke and Wicksten, 2017), to be carried far away.  
The species is also highly adaptable, able to live in an extreme range of temperatures and salinities (Konecny and Harley, 2019). Consequently, this allows the species to utilise a wide range of habitats like estuaries, harbours, and mudflats (NNSS, 2020).

Native Range and Distribution:
Orange-striped anemones are native to the Northwestern Pacific (Konecny and Harley, 2019), first being recorded in Hong Kong (NNSS, 2020). Global distribution is shown in fig. 2. In the UK it was first observed in 1896 in Plymouth (NNSS, 2020), and has since mostly been observed around the English Channel (NBN Atlas, 2024). In Scotland, multiple individuals were identified in the Loch Sween MPA between 1982 and 1985, as well as two on Orkney in 1994. The last known sighting in Scotland was on Shetland in 2003 (NBN Atlas, 2024). All recorded UK sightings are shown in fig. 3. 

Risks and Control:
As it stands, very little is understood about the effects orange-striped anemones may have on the ecosystems which they invade (Podbielski et al, 2016). Some theorised impacts include alteration of habitats and chemical fluxes or preying on the young stage of important species like oysters and mussels (Podbielski et al, 2016). 
With such little understanding of the threat posed by the species, the controls in place to prevent their spread are even more limited. At best, ongoing efforts to prevent the spread of other invasive marine species may unintentionally limit the distribution orange-striped anemones, such as awareness and prevention of marine equipment contamination.