When this happens, the thyroid gland is no longer under pituitary control. The amount of hormone it produces is dependent on levels of TSI. TSI are the direct cause of hyperthyroidism in Gravesâ disease and various immune system chemicals known as cytokines also contribute to the symptoms that occur in this disorder.
Iguanas are reptiles and nearly all reptiles lay eggs. There are some reptiles that do not lay eggs, but they are very rare. Female iguanas usually lay a clutch of eggs every year once they're mature. If there is no male iguana, she will still lay eggs, but they won't be fertile.
Iguanas, Sea Lions in Danger. The La Cumbre volcano, situated on uninhabited Fernandina Island, erupted on April 11 for the first time in four years. The volcano's last eruption occurred in May 2005, but Fernandina has more volcanic activity than any other island in the Galapagos, according to The Associated Press. Species such as marine and terrestrial iguanas, sea lions and other fauna are most at risk from the flowing lava.