Fish Tales 217They live as parasites by attaching to the side of a fish with their suction cup mouth and
using their rasping teeth to suck the fluids out of their host.
These two unsavory characters may not be our favorite cousins, but they are the only
jawless vertebrates alive today. However, the fossil record shows that jawless vertebrates had
quite a successful run. We can trace them back to the Cambrian, where we find soft-bodied
impressions in China (Shu et al. 1999) that have been named Myllokunmingia, Haikouella, and
Haikouichthys (figs. 9.8 and 9.9). These recent discoveries push the earliest vertebrates all
FIGURE 9.7. Two examples of living jawless craniates. (A) The living hagfish, Myxine. (Photo courtesy NOAA)
(B) The living lamprey, shown here clinging to glass with its sucker-like mouth and displaying its rasping
teeth, which it uses to eat a hole in the side of its prey. (Photo courtesy J. Marsden)
(B)(A)