(Please note that these animals can make great pets for people who have the experience and knowledge to properly care for them.)
Large Boids (Green anacondas, Indian and Burmese pythons, African rock pythons, reticulated pythons) - These snakes grow to gigantic sizes and can be extremely dangerous if not handled properly. There have been a number of cases where large pythons have caused serious injury and even death to children and adults. Experts often recommended that two people always be present to handle such large snakes. Most people are unable to provide proper housing and diet (rabbits, chickens, rats).
Crocodilians (Alligators, Caimans, Crocodiles) - Their size, demanding housing and feeding requirements, and aggressive nature make these animals inappropriate pets for virtually everyone. When they have worn out their novelty, owners often dump them in rivers and lakes, creating a problem for indiginous species and leaving the crocs to die a slow death. For more information, visit crocodilian.com.
Green Iguanas - Adult iguanas can reach lengths of 5 feet + and live 15 years or more. Males can become territorial and very aggressive after reaching sexual maturity. They require extremely large enclosures and a special vegetarian-only diet. According to the Green Iguana Society, over 10,000 iguanas are abandoned in the United States each year - some of them horribly abused. For more information, read Green Iguanas - Ten Dollar Sticker Price, Thousand Dollar Investment and visit Melissa Kaplan's Iguana page.
Tokay Geckos - This cute little lizard is probably the most aggressive reptile there is. With very few exceptions, Tokays do NOT become docile or tolerate handling and they have very strong jaws, capable of causing serious injury. Furthermore, a tokay gecko, once having bitten, will not readily let go. Tokays are great pets for those who are experienced in handling aggressive, fast moving reptile species - NOT BEGINNERS. For more information, www.anapsid.org/tokays.html.
Sulcata Tortoises - These tortoises can grow to 200 lbs + and live for 50-60 years. They have huge appetites and require a constant supply of fruits and vegetables. Special lighting and heating is also necessary to provide the proper warm and dry conditions. Tortoise rescue groups are full of abandoned sulcatas. For more information, visit sulcata-station.org and http://www.turtlehomes.org/usa/test.shtml.
Box Turtles - Box turtles require very specific dietary and environmental conditions. They also require a lot of room to thrive. Almost all box turtles found in the pet trade are wild-caught adults that are heavily parasitized. They are also illegal to keep in many states. For more information, visit http://www.anapsid.org/box.html and turtlehomes.org.
Red Eared Sliders - Illegal in some states, these turtles are a threat to local wildlife and are also suffering from overpopulation. They are messy, tedious to take care of, and have a very nasty bite. Red Eared Sliders are also carriers of Salmonella and for that reason, it is illegal to sell small turtles (those with a shell length of less than 4 inches) as pets in the United States. The CDC estimates that this ban prevents an additional 100,000 cases of salmonellosis among children each year. For more information, visit redearslider.com and turtlehomes.org.
Parrots (Macaws, Cockatoos, African Greys, etc.) - Parrots can live 60 years +. They require special housing, diet, and socialization. If not socialized, they can become aggressive and inflict painful bites. The average customer is not prepared for such responsibility. For more information, visit avianwelfare.org.
Monkeys - The risk of disease transfer, the inability of most people to meet the long term physical and psychological needs of monkeys, and the fact that these are wild, not domestic animals, all lead to the conclusion that monkeys simply do not make good pets. In addition, non-human primate ownership can be regulated at the local, state or national level. Even if legal at the state level, numerous cities and counties have made it against the law to keep pet primates; illegal possession can result in fines and confiscation. For more information, visit http://www.petmonkey.info/.
Wild-Caught Animals (AKA "farmed", "ranched", "captive raised", or "long term captive") - Imported or wild-caught animals are often emaciated, dehydrated, infected with parasites, and sick. Captive bred animals are healthier, live longer, and have already adapted to being in captivity. For more information, visit Imported Pets.
"Exotic" Animals - Wild and exotic animals, even those bred in captivity, still possess innate social and physical needs, and mental stimulation that cannot be met in private homes. The average person lacks the expertise to provide proper nutrition, medical care, and husbandry.
Photo Credits: Box Turtle photo by Jeff LeClere, www.herpnet.net
Red Eared Slider photo by Anita, www.turtlewife.com