Gary Bell/ Oceanwide / Piling with sponges, tunicates, and ascidians, Yorke Peninsula, South Australia, Australia

Georgette Douwma / Colonial anemones (Amphianthus nitidus) with Green urn sea squirts (Didemnum molle) (Atriolum robustum). Lembeh Strait, North Sulawesi, Indonesia.

Konrad Wothe / Slow motion clip of Wood ants (Formica rufa) on anthill, squirting formic acid to repel threat, Bavaria, Germany, April.

Alex Mustard / Nudibranch (Nembrotha cristata) climbing on a Tunicate (Polycarpa aurata) at night. This species of seaslug feeds on seasquirts. A tiny cyclopoid copepod swimming past. Yillet Yecil, Yillet Islands, M...

Constantinos Petrinos / Chromodorid nudibranch (Chromodoris annae) on Sea Squirt (Polycarpa aurata) Lembeh Strait, North Sulawesi, Indonesia.

Alex Mustard / 2020VISION / Light-bulb sea squirts (Clavelina lepadiformis), a colonial filter feeding invertebrate, fluoresce green when photographed under deep blue light. Shetland Islands, Scotland, UK, June. Did you know? Se...

Alex Mustard / 2020VISION / Light-bulb sea squirts (Clavelina lepadiformis), a colonial filter feeding invertebrate, fluoresce orange when photographed under deep blue light. Shetland Islands, Scotland, UK, June. Did you know? L...

Alex Mustard / 2020VISION / Light-bulb sea squirts (Clavelina lepadiformis), a colonial filter feeding invertebrate, Shetland Islands, Scotland, UK, June

Juergen Freund / Golden sea squirt (Polycarpa aurata) West New Britain, Papua New Guinea.

Juergen Freund / Sea squirts / ascidians / tunicates on a clam, Indo-pacific

Juergen Freund / Nudibranchs (Chromodoris lochi) crawling on a sea squirt. North Raja Ampat, West Papua, Indonesia.

Juergen Freund / Green urn sea squirt / tunicate (Didemnum molle) internal detail. Misool, Raja Ampat, West Papua, Indonesia.