Document Type

Honors Project

First Advisor

Dr. Moshe Khurgel

Degree Award Date

Fall 2019


growth curve, axolotl, urodele, total length, snout to vent length, SVL, age, salamander, amphibian, Ambystoma mexicanum, rate of growth




Growth curves of many animals have been established to control for changes in animals' metabolism and size during various experiments. Other than for early developmental stages, no such growth curves exist in the scientific literature for Ambystoma mexicanum - an aquatic salamander that is commonly used in regeneration research.

Long-term growth patterns were analyzed in this study using total length (from the tip of the snout to the tip of the tail) measurements that have been recorded over the span of 9 years. Snout to vent length (SVL) measurements were obtained for some of the animals in addition to total length sizing over the last 1.5 years. Earlier measurements were obtained by directly sizing animals with calipers. Later measurements were obtained indirectly, by taking pictures of the animals and using software to derive total length and SVL. All animals were maintained under similar housing conditions and feeding schedules.

The growth of animals of different genotypes were compared in this study: wildtype (wt), white (dd), albino (aa), and green fluorescent protein (GFP). Additionally, body lengths of animals that have not been subject to amputations were compared to those of animals that were subjects in regeneration experiments.

The results show that animals that had undergone limb regeneration lagged in growth when compared to naive animals. The analysis also suggests that SVL are more accurate measurements of growth than total length measurements. There were no significant differences between the growth rates of animals with different genotypes and pigmentation.

The sex of the animals in this study was unknown, therefore it was not possible to examine sexual dimorphism with respect to body length.

Recommended Citation

McIntyre, Sarah. “Growth Curves of the Laboratory Raised Axolotl Salamander (Ambystoma mexicanum).” Senior Honors Projects, Bridgewater College, 2019.

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