BB Ch17 Flashcards
- Amphibian is derived from the greek word “amphibios”. What does it mean?
“double life” describes the aquatic larval stage and postmetamorphic terrestrial lifestyle of many amphibians
- What 3 orders are found in the class Amphibia?
Gymnophioma (caecilians), Caudata (salamanders), and Anura (frogs)
- What are the 3 groups of Caudata?
Sirens (eel-like amphibians), primitive salamanders (hell benders and related species), advanced salamanders (mudpuppies, amphiumas, axolotls, newts, and many terrestrial species)
- What is neotony?
Condition where salamanders retain larval characteristics while becoming fully functional reproducing adults
- Which salamander species demonstrate neotony?
Hellbenders (Cryptobranchus sp.), Ambystoma mexicanum (Axolotl), Ambystoma tigrinum (tiger salamander)
- Frogs can be divided into 3 groups. What are they? Give examples.
Primitive frogs-family Discoglossidae (fire bellied toad-Bombina orientalis and midwife toad-Alytes obstetricans), Transitional frog-family Pelobatidae (spade foot frog-Scaphiopus), Advanced frogs-family Pipidae (Pipa and Xenopus) and 16 other families (Bufonidae, Dendrobatidae, Hylidae, Leptodactylidae, and Ranidae)
- How can you tell males from females in Rana catesbiana (bull frog), R. grylio (pig frog), and R. clamitans (bronze frog)?
Male-the typanum is larger than the eye and , in females, the tympanum is the same size as the eye.
- How has Xenopus laevis (African clawed frog) been used in research?
Originally used in pregnancy tests (assays). Injection of pregnant woman’s urine into the dorsal lymph sac of a female Xenopus would induce the frog to lay eggs. Used in cell and develomental biology. Can inject with commercially available hormones to ensure that the frogs reproduce year-round. Also Xenopus have been the subject of developmental toxicology investigations using FETAX assays (frog embryo teratogenesis assay: Xenopus). Xenopus has also been used in molecular biology by injecting oocysts with foreign DNA or messenger RNA to allow expression of genetic material.
- List other amphibians used in research.
Mudpuppies (Necturus)-comparative anatomy, axolotls (Ambystoma mexicanum)-developmental research, axolotls and newt-limb regeneration, frogs (bull frogs-Rana catesbiana and leopard frogs-R. pipiens)-physiology and also effects of emetics because they regurgitate easily, and antinociceptive (pain relieving) effects of analgesia
- What are the most important considerations when choosing primary enclosures for amphibians?
Should be constructed of impermeable, easily sanitized material; able to withstand multiple cage washings; adequate height to accommodate behavioral needs of climbing and jumping species; and fitted with nonabrasive lids
- What environmental conditions are amphibians susceptible to?
Dessication if environment is too dry and acidic pH (soil or substrate)
- Many amphibians will die from exposure to chlorine in water. How can water be dechlorinated?
1) Age open containers of water for 24-48 hours.
2) Add sodium thiosulfate to water.
3) Pass tap water through activated carbon filters.
4) Aerate the water.
- Cloramines, more toxic than chlorine, are sometimes added in municipal water systems. How are these removed?
Use an unused activated charcoal system. Alternatively, add sodium thiosulfate which reacts with the chloramines to form ammonia. The ammonia can be removed with zeolites.
- Most amphibians have thermal zones lower than reptiles. What are the preferred zones for tropical and temperate amphibians?
Tropical species-21-29o C (70-85o F), temperate species-18-22o C (65-72o F)
- If salamanders of the genus Plethodon are maintained at temperatures over 20 C (68 F), what will happen?
Prevents animals from assimilating food rapidly enough to meet the need of the increased metabolic rate.
- What type of lighting and light:dark cycles are recommended?
Direct exposure to bright light should be avoided. Use full-spectrum bulbs. Provide shelter to escape light. 12:12 light cycles are adequate unless breeding or trying to mimic natural habitat.
- What relative humidity is recommended for most amphibians?
80%
- Animal room airflows my dry out wet environments. How can this be alleviated?
Decrease room airflows and house in primary enclosures with minimal openings
- How often should the primary enclosures of amphibians be cleaned?
Singly housed terrestrial animals with ample floor space can be cleaned every 2 weeks with spot cleaning as needed. Group housed should be cleaned more frequently as needed.
- Can phenols be used to clean amphibian enclosures?
No, phenols are toxic and can be absorbed through the skin.
- Normally amphibians have a protective mucous layer on the skin and have the ability to secrete toxins through the skin when threatened. What is the proper way to handle these animals?
Glove should be worn that are free of powder and moistened with dechlorinated water. Do not use abrasive paper towels. Nets of soft fine mesh can be used. Small terrestrial can be restrained in 1 hand. Larger salamanders should be grasped behind the head and around the pectoral girdle with 1 hand and around the pelvic girdle with the other hand. Do not pick up by the tail as it will release! (predator avoidance)
- What are 5 methods of identifying amphibians?
Individual color patterns on the animals. Toe clipping-ineffective in long term studies because the toes regenerate. It also requires anesthesia, sterilized instruments, and hemostasis. Tattooing and freeze or chemical branding has been tried but it is not permanent. Glass or plastic beads have been sewn with nonabsorbable sutures to amphibians but they must be secure to a muscle mass or they will be shed. Lastly, passive integrated transponders have been implanted intracoelomically.
- How long should amphibians be quarantined for long term studies?
2-4 weeks minimum and longer is wild caught
- What are some zoonotic diseases that may be carried in amphibians?
Atypical mycobacterosis (Mycobacterium fortuitum, M. marinum. M. xenopi), Salmonella, and Chlamydia psittaci
- What are the 2 primary types of skin glands present in amphibians? What do they secrete and why?
Mucous glands secrete a slimy protective layer which prevents mechanical damage to skin, facilitates retention of body fluids, and provides a barrier against pathogens. Granular glands synthesize and secrete a variety of compounds that protect against predators, as well as chemicals that have antibacterial and antifungal properties. Defensive compounds can have neurotoxic, cardiotoxic, myotoxic, hallucinogenic, hypotensive and vasoconstrictive activity. Toxic alkaloids are found in poison dart frogs (Dendrobatidae), Bufo marinus, and other species can cause vomiting, respiratory paralysis, and sometimes death.
- What are the antimicrobial peptides called that are secreted in the skin of Xenopus laevis?
Magainins which inhibit G+ and G- bacteria, several fungi, and some protozoal species.
- What other chemical compounds can be secreted by granular glands?
Pheromones -courtship and mating
Dermorphins -potent opioid and endogenous analgesic
Bioadhesives -temporary entrapment of predators or adhere to female during mating
- Frogs have pronounced ribs. T/F?
False, ribs are absent or greatly reduced.
- What is the primary respiration surface of most amphibians?
skin
- What forces air in and out of lungs in amphibians which have lungs?
Movement of buccopharyngeal floor
- How many chambers are found in larval and adult amphibians?
Larval-2 chambers, adult-3 chambers
- What anatomical feature may impact the pharmacokinetics of drugs with hepatic excretion?
Hepatic portal veins drain the rear half of the amphibian’s body.
- The lymphatic system of amphibians drains directly into the venous system. The lymph is first collected into lymph sinuses. Where is the most accessible place to inject a substance that would be transported to the venous circulation?
Dorsal lymph sacs which lie SC over sacral area and lateral to midline
- Adult amphibians are herbivorous and larval stages are carnivorous. T/F
False, adults are carnivorous and larval may be herbivorous, omnivorous, or carnivorous.
- How dos Xenopus prehend food?
They direct food in with their front legs but many other species use their well developed tongue.
- Can amphibians vomit?
Yes and often use vomition as a defensive mechanism. Some frog species evert part of the stomach during regurgitation.
- What type of kidney is found in salamanders and frogs?
Mesonephric-lacks the ability to concentrate urine in excess of plasma levels
- Do amphibians secrete ammonia or urea?
Aquatic amphibians secrete ammonia and terrestrial amphibians secrete urea.
- How many cranial nerves are present in amphibians?
10, the hypoglossal nerve (cranial nerve XII) is formed by branches of the first 2 spinal nerves.
- A lateral line system (similar to fish) is well developed in larval amphibians and is retained by adults of many aquatic species. What is its function?
The linear arrangement of neuromasts on the head and along the body detect changes in water pressure and currents and function in locating prey.
- Can amphibians detect color?
Yes, 2 types of rods (red, green) are responsible for color sensitivity.
- How do amphibians detect odors?
Vomeronasal (Jacobson’s) organ
- Do amphibians live longer in northern or southern climates?
Northern
- How many years have Xenopus laevis been documented living ?
Fifteen (15) years
- What 2 types of blood cells are nucleated in amphibians?
Red blood cell and thrombocytes