Resolucion de acertijos

Vertebrates can be classified into five groups, based on their skin covering, how they reproduce, how they maintain body temperature, and characteristics of their limbs (arms and legs, or their equivalent such as wings or fins). Knowing the five classes of vertebrates and their characteristics helps you to understand more about these animals. |

The five classes of vertebrates are listed below.Fish |
Coho Salmon |

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1. Fish are ectothermic, aquatic vertebrates.
2. Their skin is generally covered with scales.
3. Their limbs are modified into fins for swimming.
4. They breathe with gills.
5. They lay eggs that must be in water. |
You probably knew most of this already, didn't you? The term "ectothermic" may be new to you. It means "external temperature" in Latin.The simpler term is "cold-blooded", that is, it has a body temperature equal to the surrounding environment. You know that fish are cold-blooded if you ever picked one up: they are as cold as the water they were swimming in. Even if you go swimming and are shivering with cold, you are always warmer than the water. "Aquatic" means that they spend their lives in the water. |
The most prominentfish at Cazadero is a visitor during the winter rains: the Coho salmon. A federally threatened species, this ocean-dwelling fish comes up Austin Creek when the winter rains raise the water level, to spawn (lay eggs) in the gravel beds that are so typical of the redwood creeks. Note that the eggs are laid in the water, not on land (reptiles and birds lay eggs on dry land). | |
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1. Amphibians are ectothermic vertebrates.
2. Their skin lacks scales, hair, and feathers, and is either smooth (like a frog) or rough (like a toad). They are dependent upon moisture and subject to desiccation; their skin must remain moist to aid in breathing.
3. They lay eggs in water, which hatch into an intermediate life form (tadpole or larva) that usually breathes with gills,and change into the adult form that breathes air and can live outside water.
4. They have three-chambered hearts.
5. They lack claws on their toes. |
You already knew all the facts that are in bold, didn't you? Let's think of the various kinds of amphibians that Cazadero has, and you can probably figure out all the characteristics of the class. The frog at the top is the Pacific treefrog,one of the most famous frogs in the world. Do you know why? It is the frog heard round the world! Most Hollywood movies have used the croaking of Pacific treefrogs when they want frog noises, because they are champion croakers. They are treefrogs, so they do not spend much of their time in water, but are found in trees. The toad (below, left) is the Western Toad, which you can find in the thousandsdown by Austin Creek in later summer when they have hatched out from their tadpole stage. The amphibian (below, right) is the California Newt. Newts are like salamanders, but they have the rougher, dryer skin like a toad. Frogs are like salamanders, and toads are like newts. They all have moist skins, through which they can breathe (they also have lungs for breathing).The salamander at the bottomis the California Slender Salamander, which is about 3 inches long but only 1/4 inch wide.The name "amphibian" comes from the Latin for "two lives", which refers to the fact that all amphibians have a larval stage (we call the larval stage of frogs and toads a "tadpole" or "pollywog") and an adult stage. This is unique in the vertebrate world, because fish, reptiles, birds, and mammals are allborn as small versions of the adult, not a completely different form. This dual life, one aquatic with gills and one terrestrial with lungs, may be representative of the evolution of animals out of water and onto dry land.Now, lets look at the characteristics of the class amphibian. You already knew that frogs were cold-blooded if you ever picked one up. You also knew that tadpoles hatched into...