What type of animals are classified as soft-bodied creatures without a spinal column?

The classification of soft-bodied creatures without a spinal column accurately refers to invertebrates. Invertebrates encompass a wide range of animals, including species such as jellyfish, octopuses, and worms. These organisms are characterized by their lack of a backbone or internal skeleton, which distinguishes them from vertebrates that possess these features.

Invertebrates make up the vast majority of animal species on Earth, demonstrating incredible diversity in form and function. They can be found in various habitats, including marine, freshwater, and terrestrial environments. The term "invertebrate" encompasses many subgroups, such as arthropods, mollusks, annelids, and other soft-bodied organisms.

Diatoms, while important as a group of algae, are not classified as animals; they are unicellular phytoplankton found in aquatic environments. Cnidarians are indeed soft-bodied animals, but they represent only one phylum within the broader category of invertebrates. The option "biospheres" refers to global ecological systems rather than a classification of animal types.

Thus, referring to invertebrates is the most accurate and inclusive answer to describe soft-bodied creatures without a spinal column.