INTEGUMENTARY COLOR CHANGES IN THE NEWLY-BORN DOGFISH, MUSTELUS CANIS

¹ From the Biological Laboratories, Harvard University

1. Mustelus canis is an ovoviviparous dogfish in which the young are born with a body length up to 33 cm.

2. At birth the young dogfishes are of a moderately dark melanophoric tint. This is doubtless the influence of the maternal body within which they have been lodged.

3. Immediately after birth these young dogfishes respond to their environment in that they change light or dark, conditions brought on by a concentration or a dispersion of their melanophore pigment.

4. Pale bands can be produced on the fins of newly-born Mustelus by cutting their nerves, as can be done with the adults.

5. A young Mustelus responds to injections of adrenalin by blanching and to pituitrin by darkening as adults do.

6. A newly-born Mustelus shows no evidence of the primary phase of color change seen in some other fishes and in some amphibians. It appears to omit this phase in its ontogeny and is born with a melanophore system that responds in the same way as this system does in the adults.