a. Northern fur seal (NFS): lateral view of male (m) and female (f) hookworm (hw). V vulva. b. NFS (mhw) buccal capsule en face view. c, d California sea lion (CSL) (fhw) buccal capsule (dorsal ventral view) anterior cutting plates ( CP). e CSL (fhw) buccal capsule, lateral view anterior cutting plates after squashing. f. CSL (fhw) lateral view of the vulva