Some Large Benthic Invertebrates Lack a Gut Because

Question

Some large benthic invertebrates lack a gut because
A) They feed on dissolved organic matter
B) No large benthic invertebrates lack a gut
C) They have very low metabolic needs
D) They have symbiotic bacteria, which provide nutrients

Accepted Answer

Some large benthic invertebrates, like certain species of deep-sea worms, lack a gut because they rely on symbiotic bacteria to provide them with nutrients. These bacteria can convert inorganic compounds into organic matter that the host can use.