Why is the number of trophic level restricted to four or five in a food chain?

Recent research by marine biologists suggests that bottlenose dolphins have names for themselves. scientists played sounds they had identified as the names of particular dolphins, putting them through a synthesizer so that they did not sound like the voices of particular dolphins. the researchers found that dolphins would respond to the names of other dolphins that they were related to or associated with, but they ignored the names of strangers. this discovery suggests a much greater degree of self-awareness in aquatic mammals than was previously suspected. if this research holds up, what does it suggest about dolphins?

Apaleontologist finds a plant fossil that shows that the plant had seeds. what can the paleontologist conclude?

Asea turtle has washed up on a remote section of a beach. this known as a stranding occurs when a dead, sick or injured sea turtle washed up on the shoreline. which statment best explain why stranding should be reported immediately to local authorities