Which term describes invertebrates large enough to be seen without a microscope living on the bottom substrate?

The term that accurately describes invertebrates large enough to be seen without a microscope that live on the bottom substrate is "benthic macroinvertebrates." These organisms are typically found in various aquatic environments, including rivers, streams, lakes, and ponds, where they play a crucial role in the ecosystem. They serve as indicators of water quality and contribute to the decomposition of organic material, thus supporting nutrient cycling.

Benthic macroinvertebrates include various species such as insects (like mayflies and caddisflies), worms, and mollusks. Their presence and diversity can provide vital information about the health of aquatic ecosystems, making them important for studies in aquatic science and environmental monitoring.

The other terms relate to different categories of organisms. Microinvertebrates refer to small invertebrates that are usually microscopic and not visible to the naked eye, macrozooplankton refers to larger planktonic organisms, and aquatic microbes denote bacteria and other microorganisms that also cannot be seen without a microscope. Understanding these distinctions is essential for grasping the complexity of aquatic habitats and the organisms that inhabit them.