Cephalochordata

Definition

Cephalochordata is a subphylum of small, fish-like marine animals known as lancelets. They are characterized by their elongated bodies and retention of the notochord throughout life.

5 Must Know Facts For Your Next Test

1. Cephalochordates possess all four key characteristics of chordates: notochord, dorsal hollow nerve cord, pharyngeal slits, and post-anal tail.
2. Lancelets are considered to be the closest living relatives to vertebrates within the chordate group.
3. Unlike vertebrates, cephalochordates lack a backbone but retain a notochord that functions as a support structure.
4. They exhibit filter-feeding behavior through their pharyngeal slits.
5. Cephalochordates have segmented muscles called myomeres, similar to those found in vertebrates.

Review Questions

• What are the four key characteristics of chordates that cephalochordates possess?
• How do cephalochordates differ from vertebrates in terms of skeletal structure?
• What feeding mechanism do cephalochordates use?

Related terms

Chordata:

A phylum that includes animals possessing at some stage of development a notochord, dorsal nerve cord, pharyngeal slits, and post-anal tail.

Vertebrata: A subphylum under Chordata characterized by having a backbone or spinal column.

Notochord: A flexible rod made out of a material similar to cartilage; present in all chordate embryos and some adult forms.