The Galapagos and Marine Sea Iguanas
By John Smith
Figure 1. Circulation of ocean currents affect water temperature
and nutrient cycling near the Galapagos Islands.
Video 1. Marine sea iguanas expelling salt. (30 seconds)
Image 1. Marine sea
iguanas rewarming and
blending in amongst the
dark basaltic rocks of the
Galapagos.
References
Lindquist, D., & Wilcox, J. (2000). New concepts for meadow restoration in the
Northern Sierra Nevada. Feather River Coordinated Resource Management.
Retrieved on February 2, 2007 from
http://www.feather-river-crm.org/publications/abstracts/ieca.htm
Moerke, A., & Lamberti, G. (2004). Restoring stream ecosystems: Lessons from
a midwestern state. Restoration Ecology 12(3): 327-334.
Monroe, J., & Wicander, R. (2006). The Changing Earth. Fourth Edition.
Thompson Publishing.
Image 2. Marine sea iguana underwater at the Galapagos
Islands. Note the algae on the rocky substrate.
Marine sea iguanas (Amblyhynchus cristatus) are only
found on the Galapagos Islands. The Galapagos are
isolated volcanic islands located west of Ecuador in the
Pacific Ocean. Due to the Cromwell Countercurrent and
deep-ocean upwelling, cold nutrient rich water is brought
to the surface to support a wide variety of underwater
algal growth and the food source of the marine sea
iguana. Due to limited resources on land, these iguanas
enter the rocky intertidal and shallow sea environment to
consume the algae that grows along the rocky bottom.
Marine sea iguanas have several unique adaptations that
allow them to survive in this environment. A gland above
their nostrils allows marine sea iguanas to “sneeze” out
salt. Without being able to expel salt, iguanas would
rapidly dehydrate as a result of their salty diet of sea
algae. Elongated tails provide for enhanced swimming
and strong claws and long nails allow iguanas to hold
onto the rocky volcanic seafloor despite strong currents
and pounding surf. They are dark in color and easily
camouflage amongst the dark basaltic rocks of the
Galapagos. Their dark color allows these ectothermic
animals to quickly rewarm and raise their body
temperature on the rocks after swimming in the cool
water just off shore. It is easy to see that the unique
environmental conditions of the Galapagos have given
rise to uniquely adapted organisms such as the marine sea
iguana.