BIO 109 Home
Questions | Answers

1. Never handle venomous species and never place your hands or feet anywhere you can't see.

2. Bark scorpion, black widow, brown spider, gila monster (debatable), coral snake, and rattlesnakes.

3. Venomous species inject toxins into their victim (e.g., by teeth, stinger, fangs, etc.). Rattlesnakes and wasps are examples. Poisonous species secrete toxins within their body or onto their skin. For example, the Sonoran Desert Toad is poisonous; you would never want to eat one but you don't have to worry about one attacking you. A rattlesnake is venomous, you can eat them, but never let them bite you.

4. Hemolytic toxins: affect the circulatory system by destroying blood cells and vessels ("hemo" means blood). Symptoms include severe pain, swelling, discoloration, and local tissue death. Shock can occur. Example: most rattlesnakes. Neurotoxins: affect the nervous system ("neuro"). Symptoms may include local pain, headache, dizziness, nausea, cramping, facial paralysis and occasionally death by circulatory arrest or respiratory paralysis. Examples include Black Widow, Scorpions, and Coral Snake. Other toxins include the protein-destroying toxins of brown spiders and the pain-causing toxins of gila monsters.

5. Venom is used for food digestion, for subduing prey, and for defending against predators and other potential threats.

6. They have to have special equipment (venom glands, fangs, etc.), and venom is expensive to produce (materials and energy).

7. When used to subdue prey, they match the amount of venom to the prey type and size; for example, more venom is used when the prey size is larger or the prey can get away easier (e.g., birds). They try to avoid having to use venom defensively by retreating, by using camouflage to avoid being seen in the first place, by warning the potential aggressor that they are dangerous, and by giving dry bites (biting, but not injecting venom).

8. Cryptic coloration is coloration that makes it difficult to see the animal (camouflage). Aposematic coloration is warning coloration that usually is bright, bold, and memorable (e.g., the orange and black of wasps).

9. Batesian mimics are species that only pretend to be dangerous or inedible. Thus they receive the value of defense without the expense.

10. Nocturnal means active at night, diurnal means active during daylight, and crepuscular means active at dawn and dusk.

11. Bark scorpion. Identified by having long, thin pincers.

12. Black widows: females are dangerous and can be identified by black body containing an hourglass shaped marking on the bottom side of the large abdomen. Brown spiders: identified by 3 pairs of eyes in a horseshoe shape on the top of the cephalothorax (head).

13. Gila Monster and Mexican Beaded Lizard.

14. Coral snakes have red, yellow (or white), and black bands that go all the way around the snake and the red and yellow bands touch each other ( remember "Red and yellow kill a fellow, red and black friend of Jack").

15. The number of times it has shed its skin (if no segments have been lost). Because they can shed their skin a variable number of times each year (depends on amount of food consumed, etc.), you cannot tell their age.

16. Eyes (vision), nostrils (smelling), body (ground vibrations - similar to hearing), Pit Organ (senses heat), Jacobson's Organ (senses chemicals brought to it by the tongue to augment smell). The tongue merely serves to collect the chemical scents from the ground and air and to deliver the chemicals to the Jacobson's Organ on the roof of the mouth to give stereoscopic smell.