Answer:
b.) because its the only thing he can really control and it stays the same through out the entire experment
Explanation:
Answer:
Dr Poole worked in Gorongosa park and he made the observation of most females being tuskless as a result of the selective pressure caused by poaching.
Although male elephants are also affected by this in which some don’t also have tusks the percentage is low when compared to the female elephants.
Answer:
B. Epithelial
Explanation:
The respiratory segment comprises most of each nasal cavity, and is lined with ciliated pseudostratified columnar epithelium (also called respiratory epithelium).
Answer:
Option 2: Spiracles.
Explanation:
Cartilaginous fish (also called Chrondricytes) have a skeleton of cartilage, instead of bone. There are two subclasses - Elasmobranchii and Holocephali. Sharks, rays, skates and sawfish are elasmobranchs while chimeras are holocephali.
Here’s a list of features of cartilaginous fish in comparison to bony fish:
1. Cartilage skeleton: unlike bony fish that have a skeleton made of bones (just like other terrestrial vertebrates), the skeleton of cartilaginous fish is made of cartilage.
2. Spiracles: this is a modified gill of sorts, it aids with respiration and is found slightly behind each eye. It leads directly to the mouth. Most cartilaginous fish possess this organ (exceptions are present, such as hammerhead sharks). Bony fish do not possess spiracles.
3. Ampullae of Lorenzini: absent in bony fish, these organs are electroreceptors that form a network of pores filled with a form of jelly that can transmit electrical signals. It allows the cartilaginous fish to sense electric fields in the water (such as the movements of a fish struggling), magnetic fields and temperature. Some bony fish such as sturgeon and lungfish may possess these organs, however research is still ongoing.
4. Claspers: male cartilaginous fish possess an organ known as claspers at their pelvic fin. This is used during reproduction to transfer the sperm into the female for fertilisation. As such, internal fertilisation occurs in cartilagonous fish. Bony fish do not possess this organ, and external fertilisation occurs.
There are many other characteristics that differentiate cartilaginous fish from bony fish. They're an extremely fascinating group of animals that unfortunately, is decreasing in numbers. Very little is known about many of these animals, so it is important that we do our best to conserve the sharks, rays, sawfish and chimeras before we lose them forever.
