Herpetology

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Herpetology
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Herpetology is an event for the 2018 season in Division B and Division C that deals with the identification and life science of different specimens of amphibians and reptiles.

This article mainly deals with the general concepts of this event. Specific identification info can be found on Herpetology/Herpetology List.

The official taxonomy list used for this event for the 2018 season can be found here. States may also have their own lists, which can be found on the respective state's website.

Introduction to Herpetology

Amphibians VS Reptiles

While most amphibians are tied to water throughout their lives, reptiles of many species generally entirely terrestrial. The adaptational differences of each represent this difference.

Amphibian Reptile
Eggs Moist and spongy exterior Tough and leathery outer shell
Skin Moist glandular skin Keratinized, rough skin/scales
Reproduction External generally Internal generally
Origin Lobe-finned fishes Amphibians
Feet Often webbed, without claws Clawed, less often webbed
Respiration Lungs, skin, and/or gills Lungs, skin in rare cases.

Internal Anatomy

Circulatory System: consists of two loops.

  • Pulmonary loop - from heart to lungs and back
  • Systemic loop - from heart to body tissues and back

Hearts in all herps other than crocodiles consists of two atria and one ventricle somewhat divided by a septum. Contraction of heart keeps oxygenated and deoxygenated blood separate even though ventricle isn't completely divided. In crocodiles, two atria and ventricles exist.

There are two main ways in which adult amphibians respire:

  • Pulmonary respiration - breathing through lung by positive-pressure breathing
  • Cutaneous respiration - respiration through the skin

Nervous System: brain is similarly sized (relatively) in amphibians and reptiles.

In reptiles, the cerebrum (used for controlling behavior) is larger than amphibians. Optic lobes are also large, due to the fact that many reptiles rely on sight for hunting. Some reptiles and amphibians have nictitating membrane which is a transparent,movable membrane that covers the eyes allowing them to see with their 'eyelids' closed.

Hearing is also important. Sound waves heat the tympanum and then are transferred to the inner ear through the columella. Snakes lack a tympanum and are effectively deaf. They are however able to sense vibrations caused by sound through a touch. They detect these ground vibrations which are transferred to columella by the bones of jaw.

The Jacobson's organ is an extra sense organ in the roof of the mouth of reptiles. This organ is used to detect scents in the air. Reptiles use their forked tongue to gather chemicals from the environment and transfer it to the back of their mouth. These scent chemicals are then analyzed by the brain to find prey by using the two segments of the forked tongue independently gathering scent, and determining in the brain the direction of the scent through the sensitivity on each fork. While reptiles can smell with their nostrils, the jacobson organ is vastly more sensitive and important.

Another 'sixth' sense is present in pit vipers. A heat-sensitive pit beneath eyes allows the snake to detect heat. This allows them to locate warm blooded prey instantly in any light.

Reproduction

Frog mating positions

Fertilization - the joining of egg and sperm

  • Internal Fertilization - fertilized within female's reproductive tract
  • External Fertilization - fertilized outside body

Reptilian Patterns of Reproduction - division of reproduction methods by how long eggs stay within female and in how eggs are provided with nutrition

  • Oviparity - female's tract encloses egg in tough shell which is then deposited
  • Ovoviviparity - eggs retained in female's body before being either laid shortly before hatching or hatching within body
  • Viviparity - shell is not formed around egg and young mature in female's body; nutrients often delivered by placenta


Behavior

Many behavioral aspects of reptiles and amphibians are due to their thermoregulation strategies. Each of these species are ectotherms (cold-blooded and gaining heat from environment rather than metabolism). This energy saving strategy leads to several behavioral adaptations.

  • Activity - Many ectotherms have optimum temperatures of function (due to the optimum temperatures of enzymes), this results in many organisms in cooler habitats being most active in midday and many organisms in desert habitats to be more nocturnal. The other pros and cons of diurnal/nocturnal are listed below.

Other reasons to be diurnal include easier sight and communication as well as more common prey in some habitats. Reasons to be nocturnal include less competition for food and fewer predators in some habitats.

  • Aestivation - During cold or dry seasons, some organisms 'hibernate' in order to retain energy.

Other aspects of behavior good for review are mating rituals, how they interact with other organisms (aggressive or passive), and how they obtain food.

Conservation

Populations of various reptiles have diminished for several reasons. First of all is their (or their eggs) use as food in many cultures. (Snapping Turtle soup is actually quite tasty.) "Rattlesnake roundups" have occured in some states as recreational activities. Snakes are gathered to be killed by visitors who do so in belief that killing snakes protect public. Every year in Sweetwater, Texas, about 1% of the entire rattlesnake population of Texas is slaughtered. Some attendees claim that this is justified due to the fact that they collect venom, however the venom is useless for most any research as it is not collected in a sterile environment. Some are also gathered for use as folk medicine. Snake venom has use in medical research. Habitat destruction is also hurting various populations.

Amphibian populations have been mysteriously declining for several years. There are several proposed reasons for this decrease. Some believe thinning of the ozone layer increases the amount of UV B radiation that reaches sensitive eggs, embryos, and larvae causing them to die. Herbicides, pesticides, and fertilizers also have killed amphibians when interfering with their natural hormones. Habitat destruction and disease have also lead to a large amount of decrease in population.

One of the largest threats to anurans (frogs and toads) is a lethal fungal infection that has been expanding in prevalence and range in recent year. This disease, known as chrytridiomycosis, is caused by the chrytid fungus Batrachochytrium dendrobatidis. The disease is thought to increase in range with global warming. This disease is responsible for large numbers of frog death, and are among the leading causes of the extinction of several frog species, and possible more to come.

Helpful Hints

1) If they allow a field guide, make your own, and know where everything in it is. It is advisable to do this in a large binder with a lot of tabs so you can stay organized.

2) Be able to identify quickly, you should be able to do most if not all identification without resources.

3) Do not rely on your field guide, memorize as much as you can.

4) Make flashcards or online quizzes to study.

5) Put post-it flags in your field guide to get to major sections easily.

6) Print out diagrams and helpful pictures if needed, and put them into your field guide.

7) Know where everything is in your field guide, as this will be much quicker than jumping to the index and searching for the page.

8) Some field guides will only have the Western specimens and some will only have the Northeastern. Be sure that you know both Western and Northeastern specimens, along with Central.

9) Know the sounds various reptiles and amphibians make.

Vocab

Organizations and Acts

  • Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES): An international agreement among governments
  • International Union for Conservation of Nature and Natural Resources (IUCN): An international organization working in the field of nature conservation and sustainable use of natural resources composed of both government and civil society organizations
  • IUCN Red List of Threatened Species: Founded in 1964, it is the world’s most comprehensive inventory of the global conservation status of biological species.
The different categories of species the IUCN Red List assigns.
  • Endangered Species Act of 1973 (ESA): Designed to enact provisions outlined in CITES, it was signed into law by Richard Nixon on December 28, 1973. It declares the categories E (endangered), T (threatened), C (candidate), ES/A (not endangered but similar in appearance to an endangered species), TS/A (not threatened but similar in appearance to a threatened species), XE (experimental essential), and XN (non-existential population)
  • Species at Risk Act (SARA): Entered Canadian law on December 12, 2002, it is designed to enact provisions outlined in CITES, by the designation of the COSEWIC.
  • Committee on the Status of Endangered Wildlife in Canada (COSEWIC) or Comité sur la situation des espèces en péril au Canada (COSEPAC): An independent committee of wildlife experts and scientists that identifies species at risk in Canada: it designates X (extinct), XT (extirpated in Canada), E (endangered), T (threatened), SC (special concern), and NAR (not at risk).
  • Canada Wildlife Act: It specifies requirements for a geographic area in Canada to be designated a National Wildlife Area by the Canadian Wildlife Service division of Environment Canada. "The purpose of wildlife areas is to preserve habitats that are critical to migratory birds and other wildlife species, particularly those that are at risk." Further, the Wildlife Area Regulations, a component of the Canada Wildlife Act, identifies activities which are prohibited on such areas because they may harm a protected species or its habitat. In some circumstances, land use permits may be granted to individuals, organizations, or companies if the intended use is compatible with conservation of the area. Personal activities such as “hiking, canoeing, photography and bird watching can be carried out without a permit in most areas”.
  • U.S. Fish and Wildlife Service (USFWS or FWS): Dedicated to the management of fish, wildlife, and natural habitats, it is an organization within the US Department of Interior. Its mission is "working with others to conserve, protect, and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American people".

Behavior

  • Fossorial: Adapted to digging and living underground
  • Natatorial: Specialized for swimming
  • Benthic: Living on the benthos (bottom of an ocean, lake, or river)
  • Motile: Having the capacity to move from one place to another
  • Sessile/Sedentary: Fixed in one place
  • Dormancy: A period in an organism’s life cycle when growth, development, and physical activity are temporarily stopped, minimizes metabolic activity and helps an organism conserve energy
  • Predictive dormancy: When an organism enters a dormant phase before the onset of adverse conditions
  • Consequential dormancy: When an organism enters a dormant phase after the onset of adverse conditions
  • Hibernation: Mechanism used by many mammals to reduce energy expenditure and survive food shortage over the winter, prepares by building up body fat, undergoes many physiological changes including decreased heart rate (by as much as 95%) and decreased body temperature
  • Diapause: Predictive delay in development in response to regular and recurring periods of adverse environmental conditions, predetermined by an animal’s genotype
  • Estivation/aestivation: Consequential dormancy in response to very hot or dry conditions
  • Brumation: Reptiles generally begin brumation in late autumn (more specific times depend on the species). They often wake up to drink water and return to "sleep". They can go for months without food. Reptiles may eat more than usual before the brumation time but eat less or refuse food as the temperature drops. However, they do need to drink water. The brumation period is anywhere from one to eight months depending on the air temperature and the size, age, and health of the reptile. During the first year of life, many small reptiles do not fully brumate, but rather slow down and eat less often. Brumation is triggered by lack of heat and the decrease in the hours of daylight in winter, similar to hibernation. This differs from hibernation because the reptiles do not go into a sleeping state. Originally proposed by Mayhew (1965) “to indicate winter dormancy in ectothermic vertebrates that demonstrate physiological changes which are independent of body temperature.”

Note: Hibernation and brumation are sometimes used interchangeably for reptiles and amphibians.

  • Torpor: A state of decreased physiological activity, usually by a reduced body temperature and metabolic rate, some reptiles undergo this during short cooling periods, reptiles usually do not undergo this in the winter, mammals undergo this during hibernation
  • Solitary: Lives alone
  • Diurnal: Active during day
  • Nocturnal: Active during night
  • Crepuscular: Active during dawn and dusk (twilight)
  • Matutinal: Active during morning, wake up earlier than diurnal organisms, mostly bees
  • Vespertine: Active during evening, wake up at around the same time as nocturnal, become active before nocturnal organisms

Reproduction/Life Cycle

  • Viviparity: Development of young inside mother leading to live birth, e.g. placental viviparity in humans
  • Ovoviviparity, ovovivipary, ovivipary: The egg grows inside the mother leading to live birth, embryos have no placental connection with mother and receive nourishment from an egg sac, e.g. in boas
  • Ovuliparity: Lay unfertilized eggs, no development inside mother, males fertilize eggs externally
  • True oviparity: Lay fertilized eggs, no development inside mother, fertilization is internal, whether the males insert their sperm in the female or the females actively or passively pick it up
  • Iteroparous: Offspring are produced in more than one group and across multiple seasons
  • Gonochoric/gonochoristic/dioecious: Two distinct sexes
  • Sexual: Reproduction that involves combining of two sets of genetic material, male and female: all animals undergo sexual reproduction.
  • Asexual: Where the daughters are genetically identical to the parents
  • Monogamy: One male mates with one female exclusively
  • Polygamy: Umbrella term for non-monogamous mating
  • Polygynandrous: Multiple males mate indiscriminately with multiple females
  • Polygyny: One male gets exclusive mating rights with several females
  • Polyandry: One female gets exclusive mating rights with several males
  • Copulation: The union of the male and female sex organs
  • Cuckoldry: Mostly in fish, a variant of polyandry dominated by large and aggressive males
  • Hermaphroditism: When a given individual in a species possesses both male and female reproductive organs or can alternate between possessing first one and then the other, usually sequential from female to male (protogyny), less common for a male to switch to a female (protandry)
  • Sexual cannibalism: When a female animal kills and consumes a male before, during, or after copulation, confers fitness advantages to males and females
  • Sexual coercion: When the males dominate sexually by force and size
  • Parthenogenesis: A form of asexual reproduction in which growth and development of embryos occur without fertilisation, e.g. whip-tailed lizards since males are rare
  • Unisexuality: When a species is all-male or all-female
  • Tournament species: When members of one sex (usually males) compete in order to mate
  • Heterochrony: Developmental change in the timing or rate of events leading to changes in size and shape
  • Neoteny: Delayed somatic development with constant reproductive development, leads to paedomorphism, e.g. larval gills in adult salamanders in axolotls (family Ambystomatidae, Ambystoma mexicanum)
  • Progenesis/paedogenesis: Constant somatic development with accelerated reproductive development, leads to paedomorphism
  • Paedomorphism: Retention of larval traits of adults

Anatomy

  • Anatomy: Bodily structure of animals
  • Morphology: Form of animals and the relationships between structures
  • Physiology: Normal functions of living organisms and their parts
  • Ectothermic: “Cold-blooded”, relying on heat acquired from the environment and behavioral adaptations to regulate body temperature
  • Endothermic: “Warm-blooded”, depending on or capable of the internal generation of heat
  • Heterothermic: Can switch between poikilothermic and homeothermic strategies, e.g. bats and hummingbirds which are homeothermic when active and poikilothermic at rest
  • Regional heterothermy: Able to maintain different temperature zones in different regions of the body
  • Poikilothermic: Fluctuating body temperature, naked mole rat is the only mammal thought to be poikilothermic
  • Homeothermic: Maintains thermal homeostasis
  • Bilateral symmetry: Looks the same on both sides of an axis
  • Radial symmetry: Looks like a pie, can be cut in to roughly identical pieces
  • Spherical symmetry: Resulting parts look the same if cut through the center
  • Asymmetry: When symmetry is incomplete or not present
  • Dorsal: Upper side/back
  • Ventral: Underside/abdomen
  • Anterior: Front
  • Posterior: Behind
  • Superior: Above
  • Inferior: Below
  • Sexual dimorphism: When two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs: the opposite is monomorphism

Basic Turtle Anatomy

  • Carapace: Upper shell of turtle
  • Plastron: Lower shell of turtle
  • Bridge: Connects carapace and plastron
  • Keel: Central ridge
  • Straight carapace length (SCL): Length of the turtle’s carapace measured with a pair of large calipers
  • Scute: Thickened horny or bony plate

Ecology

  • Evolution: The gradual change in genetic material of a population
  • Natural selection: The breeding for specific traits by the environment
  • Speciation: Formation of a new species
  • Reproductive isolation: When two populations can no longer interbreed
  • Ring species: When two populations that cannot interbreed are living in the same region and connected by a geographic ring of populations that can interbreed: See diagram.
A ring species: The populations connected with lines can interbreed, while the two populations at the end of the arrows cannot.
  • Biodiversity: The variety life in the world or an ecosystem
  • Riparian: Living or located adjacent to a waterbody
  • Nearctic: A biogeographic province, the northern part of the New World, includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
  • Endemic/precinctive: The ecological state of a species being unique to a defined geographical location
  • Cosmopolitan distribution: Range extends across all or most of the world in appropriate habitats
  • Ephemeral: Having a short life cycle
  • Perennial: (Of a plant) living for several years, generally bloom for one season, (of a stream or spring) flowing throughout the year
  • Annual: (Of a plant) dying every winter, produce more flowers over more time
  • Asl/Amsl: Above (mean) sea level
  • Masl/Mamsl: Meters above (mean) sea level

Reference

  • National Audubon Society Field Guide to Reptiles and Amphibians: North America
  • Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition; Peterson Field Guide to Western Reptiles and Amphibians

Day of the Event

First of all, do not panic. Panicking will only make you go slower and cause unnecessary mistakes. Make sure that both you and your partner are calm and relaxed, confident, and ready to blow away your competition. Bring two pencils and pens, just in case. Make sure you don't speak loudly, talk in hushed tones or whispers. Write neatly and legibly. Be 100% sure that the station you're on is the station you are writing answers for on your answer sheet. Do not spend more than half of the time trying to identify the specimen, go on to the questions and try to figure them out logically.

Sample Questions

Iguana.PNG

1. Identify the family and genus of this lizard

2. What kind of teeth does this species of lizards have?

3. Are these lizards principally herbivores or carnivores?

Whiptail.PNG

1. Identify the family and genus of this lizard

2. What is unique about the way certain species of this lizard produce?

3. What do these lizards eat?

Links

Biological ID Events
Herpetology · Ornithology · Forestry · Entomology · Invasive Species