English: The inner filter (“house”) of Bathochordaeus charon (a–c) compared to B. stygius (d–f) are readily distinguishable in high-definition video, taken by MBARI ROVs. Bathochordaeus charon is larger in size relative to its inner filter (if) than is B. stygius, which also has more conspicuous supply passages (sp) through which water is diverted to either filter. The inner filter of B. charon is less convoluted than B. stygius and has fewer chambers (compare c, f). Plate B demonstrates that the spiracles (s) can be seen on high-definition video. Scale bars ~ 2 cm, a–f