Definition

Noun: A hydrozoan is a type of colonial aquatic animal belonging to the class Hydrozoa. These are coelenterates (cnidarians) where the life cycle is typically dominated by the polyp stage. They are often small, marine organisms that form colonies, though some species exist as solitary polyps or medusae.

Usage and Examples

• Noun:
  • The biologist studied the hydrozoan attached to the dock's pilings.
  • Many hydrozoans, like the Portuguese man o' war, appear to be a single organism but are actually a colony of specialized polyps.

Advanced Usage

• In scientific classification, the term hydrozoan specifies organisms within the class Hydrozoa, distinguishing them from other cnidarian classes like Anthozoa (corals, sea anemones) or Scyphozoa (true jellyfish).
  • The research focused on the evolutionary development of the hydrozoan nervous system.

Variants and Related Words

• Hydrozoa (n): The scientific class name to which hydrozoans belong.
• Hydroid (n): Often used as a synonym for the polyp form or stage of a hydrozoan, especially when referring to the colonial, sedentary phase.
  • The hydroid colony filtered plankton from the water.

Synonyms

• Hydroid (when referring specifically to the polyp form)
• Colonial cnidarian (a broader descriptive term)

Notes on Different Meanings

The term hydrozoan has a precise, specialized meaning in marine biology and zoology. It does not have common idiomatic or figurative uses. Its definition is consistently tied to this specific class of cnidarian animals.

Noun

1. colonial coelenterates having the polyp phase dominant