1. A group of marine animals including jellyfish and sea anemones; formerly used as a taxonomic classification for organisms without a true brain or nervous system.
Usage: archaic; scientific; plural form; singular is acalephe; largely obsolete in modern taxonomy

Examples

• The acalephae were once thought to represent a distinct class of marine life.
• Early naturalists classified acalephae separately from other sea creatures.
• Modern biology has reorganized the acalephae into more precise phyla.
• The term acalephae reflects outdated understanding of jellyfish anatomy.
• Specimens of acalephae were commonly studied in 19th-century marine biology.