Fig. 1 in Living Together in the Plankton: A Survey of Marine Protist Symbioses

Fig. 1. Light microscopic images of living symbiont-bearing open ocean protists. a – radiolarian showing the central capsule (Cp) containing the nucleus and surrounding cytoplasm, and external to it, long-tapered, radiating pseudopodia known as axopodia (Ax) appearing as a bright halo, including numerous golden-hued algal symbionts on the axopodia (arrows). Scale bar: 500 µm; b – planktonic foraminiferan bearing a calcitic shell (Sh) and peripherally radiating calcite spines that are covered by pseudopodial cytoplasm bearing scattered algal symbionts (arrows). The small greenish, rounded shell chamber contains dense clusters of symbionts within the intrashell cytoplasm. Scale bar: 100 µm; c – composite image of a portion of a colonial radiolarian with numerous central capsules containing dinoflagellate symbionts (arrows) in the peripheral cytoplasm of the central capsules. The entire colony is enclosed within a optically clear spherical gelatinous sheath. This portion of the colony is illuminated from the lower right-hand side. Scale bar: 500 µm; d – the dinoflagellate Noctiluca scintillans (green form) with numerous living prasinomonad algal symbionts (Pedimonas noctilucae), appearing as clumps of green particles, scattered throughout the cytoplasm. Scale bar: 200 µm.