David Shale / Hydromedusa/ Trachymedusa (Crossota sp) from approx 2700m, mid Atlantic ridge, June 2010

Doug Perrine / Flower Hat Jelly / Jellyfish (Olindias formosa), a rare hydromedusa with fluorescent tentacle tips. Endemic to Brazil, Argentina, and southern Japan.

David Shale / Hydromedusa / Trachymedusa (Crossota sp) showing tentacles, from approx 2700m, mid Atlantic ridge, June 2010

David Shale / Hydromedusa / Trachymedusa (Crossota sp) from approx 2700m, mid Atlantic ridge, June 2010

Ingo Arndt / Hydromedusae (Calycopsis borchgrewinki) with extended tentacles, Weddell Sea, Antarctica

David Shale / (Octophialucium funerarium) hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Chromatonema rubrum) a hydromedusan jellyfish, deep sea Atlantic ocean

Doug Perrine / Flower Hat Jelly / Jellyfish (Olindias formosa), a rare hydromedusa with fluorescent tentacle tips. Endemic to Brazil, Argentina, and southern Japan.

Doug Perrine / Flower hat jelly / jellyfish (Olindias formosa) captive, a rare hydromedusa with fluorescent tentacle tips, found off Brazil, Argentina, and southern Japan

Doug Perrine / Flower hat jelly / jellyfish (Olindias formosa) captive, a rare hydromedusa with fluorescent tentacle tips, found off Brazil, Argentina, and southern Japan

Nature Production / Elegant Jellyfish (Tima formosa) Japan

David Shale / Benthopelagic Hydromedusa, Trachymedsa (Veragonema sp) from mid Atlantic ridge, Depth approx 2700m, June 2010

David Shale / Benthopelagic Hydromedusa, Trachymedsa (Veragonema sp) from mid Atlantic ridge, Depth approx 2700m, June 2010

David Shale / Hydromedusa / Trachymedusa (Crossota sp) Depth approx 2700m, mid Atlantic ridge, June 2010, Close-up detail

David Shale / Deepsea Hydromedusa / Trachymedusa (Benthocodon sp) approx 2700m, Mid Atlantic ridge, June 2010

David Shale / Mesopelagic hydromedusa jellyfish {Aeginura grimaldii} Gulf of Maine, Atlantic

David Shale / Mesopelagic hydromedusa jellyfish {Aeginura grimaldii} Gulf of Maine, Atlantic

David Shale / Mesopelagic hydromedusa jellyfish {Aeginura grimaldii} Gulf of Maine, Atlantic

David Shale / Mesopelagic hydromedusa jellyfish {Aeginura grimaldii} Gulf of Maine, Atlantic

David Shale / Mesopelagic hydromedusa jellyfish {Aeginura grimaldii} Gulf of Maine, Atlantic

Ingo Arndt / Hydromedusae (Calycopsis borchgrewinki) with extended tentacles, Weddell Sea, Antarctica

Ingo Arndt / Hydromedusae (Calycopsis borchgrewinki) with reflection on water surface, Weddell Sea, Antarctica

David Shale / Deepsea hydromedusan jellyfish (Aeginura grimaldii), deep sea Atlantic ocean

David Shale / (Melicertum octocostatum) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Melicertum octocostatum) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Chromatonema rubrum) a hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / Deepsea hydromedusan jellyfish (Aeginura grimaldii), deep sea Atlantic ocean

David Shale / (Octophialucium funerarium) hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Melicertum octocostatum) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Chromatonema rubrum) a hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Phialella quadrata) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / Midwater hydromedusan jellyfish (Aeginura grimaldii), deep sea Atlantic ocean

David Shale / (Melicertum octocostatum) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Chromatonema rubrum) a hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Phialella quadrata) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Octophialucium funerarium) hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Melicertum octocostatum) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Phialella quadrata) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Octophialucium funerarium) hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Melicertum octocostatum) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / {Leuckartiara octona} small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Octophialucium funerarium) hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Chromatonema rubrum) a hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Melicertum octocostatum) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / {Leuckartiara octona} small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / Small hydromedusan jellyfish {Aglantha sp}, deep sea Atlantic ocean

David Shale / (Octophialucium funerarium) hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Melicertum octocostatum) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Chromatonema rubrum) a hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Octophialucium funerarium) hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Melicertum octocostatum) small hydromedusan jellyfish, deep sea Atlantic ocean

David Shale / (Chromatonema rubrum) a hydromedusan jellyfish, deep sea Atlantic ocean

Jeff Rotman / Many-ribbed hydromedusa {Aequorea aequorea} British Columbia, Canada