Identification - Dichotomous Keys

Explanation
The correct answer is "Rounded caudal fin. Forked caudal fin." This is because a dichotomous key is a tool used to identify organisms based on a series of paired statements. In this case, the statements refer to different characteristics of the fish. The first statement "Rounded caudal fin" describes a fish with a rounded tail fin, while the second statement "Forked caudal fin" describes a fish with a tail fin that is divided into two lobes. By comparing these two statements, one can determine the difference between fish with rounded caudal fins and those with forked caudal fins.

Explanation
The presence of antennae could be used to distinguish between arachnids and insects. Arachnids, such as spiders, scorpions, and ticks, do not have antennae, while insects, such as beetles, flies, and bees, typically have antennae. Therefore, the presence or absence of antennae can be a key characteristic in differentiating between these two groups of organisms.

Explanation
The observation that the plant's leaves curl up on the edges would be useful in determining its identity with a dichotomous key because this characteristic can help differentiate it from other plants. The dichotomous key is a tool that uses a series of choices to identify an organism based on its characteristics. By noting that the plant's leaves curl up on the edges, the scientist can use this as a distinguishing feature to narrow down the options in the dichotomous key and determine the plant's identity.

Explanation
In the given illustration, the width of the thorax is the structure that is identical in all three beetle species. This means that regardless of the species, all three beetles have the same width of the thorax.

Explanation
The fish described in the question has eyes on the side of its head and a wide body covered in spots. Among the given options, the puffer fish is the most likely choice because puffer fish typically have eyes on the side of their head and their bodies are often wide and covered in spots. Therefore, the fish caught is most likely a puffer fish.

Explanation
Based on the given information, the organism depicted in the illustration is a dragonfly.