Carcinonemertes errans larva collected in January 2013, note four eyes (left). Juvenile C. errans which was collected from an adult male Dungeness crab. Note two eyes (right). Scale bars 100 µm.
Carcinonemertes errans
Sequence Data: 16S, COI
Observed in Coos Bay: Jan-Mar, July, Sep-Oct, Dec
The larvae of Carcinonemertes errans are easily recognizable. Unlike many hoplonemertean larvae, these larvae do not have a prominent blade-like apical tuft. They are fast swimmers, are pinkish-orange in color, and have two pairs of sub-epidermal eyes, and a small posterior larval cirrus. The anterior pair is maintained through larval metamorphosis (on the host species, Cancer magister). The eyes of posterior pair, which are sometimes so close together they appear as a single ocellus, are lost during metamorphosis (above right).
Carcinonemertes errans juveniles settle and grow into adulthood on the Dungeness Crab, Cancer magister, where they make a living as egg predators. C. errans adults pierce crab eggs with nail-like stylets on their eversible proboscis and suck out the contents. Tens of thousands of C. errans individuals can be found on a single crab host and they are capable of reducing the crab’s egg mass by as much as 60 % (Wickham 1980; Kuris 1993).
Interestingly, members of the Maslakova lab discovered that another nemertean species readily attacks and ingests C. errans larvae and juveniles. We maintained newly metamorphosed juveniles of the larva pilidium recurvatum (Riserius sp.) into adulthood (over 1.5 years) on a diet consisting solely of C. errans larvae (wild-caught) and juveniles (collected from male Dungeness crab) (Hiebert et al. 2013).