Deuterostome

Definition

A deuterostome is a major group of animals characterized by their embryonic development where the anus forms before the mouth. This developmental pattern distinguishes them from protostomes, which develop the mouth first. Deuterostomes include diverse organisms such as echinoderms and chordates, both of which exhibit unique features that contribute to their evolutionary significance and ecological roles.

5 Must Know Facts For Your Next Test

1. Deuterostomes are divided into two main groups: echinoderms and chordates, both showcasing distinct body plans and developmental patterns.
2. Echinoderms display a unique radial symmetry as adults, while their larvae are bilaterally symmetrical, showcasing an interesting aspect of their development.
3. Chordates possess key features like a notochord, dorsal nerve cord, and pharyngeal slits during at least one stage of their life cycle.
4. The coelom in deuterostomes develops from an outpocketing of the embryonic gut, unlike protostomes, where it forms by splitting the mesoderm.
5. The deuterostome developmental pattern is significant because it has implications for evolutionary relationships among animals, helping to trace lineage and diversification.

Review Questions

• How do deuterostomes differ from protostomes in terms of embryonic development?
  • Deuterostomes differ from protostomes primarily in the sequence of embryonic development. In deuterostomes, the anus develops before the mouth during early stages of formation. This contrasts with protostomes, where the mouth is formed first. Additionally, the way the coelom forms is different; in deuterostomes it arises from an outpocketing of the gut.
• What are some key characteristics of echinoderms and how do they illustrate the diversity within deuterostomes?
  • Echinoderms showcase several key characteristics that highlight the diversity within deuterostomes. They have a unique water vascular system that aids in movement and feeding, along with a radial symmetry as adults. Their larvae exhibit bilateral symmetry, indicating a complex developmental pathway. This duality showcases evolutionary adaptations to their marine environments while maintaining common ancestral traits with other deuterostomes.
• Evaluate the evolutionary significance of the deuterostome lineage in relation to chordates and their adaptations.
  • The evolutionary significance of the deuterostome lineage is profound, particularly when evaluating chordates and their adaptations. As chordates evolved from deuterostome ancestors, they developed key innovations such as a notochord and a dorsal nerve cord that facilitated complex nervous systems and vertebrate characteristics. This lineage highlights how fundamental developmental processes contribute to major evolutionary milestones, allowing for the vast diversity seen in vertebrates today, including adaptations for land and aquatic environments.

Related terms

Protostome:

A group of animals characterized by the mouth developing before the anus during embryonic development, including species like arthropods and mollusks.

Echinoderm: A group of marine animals known for their radial symmetry and unique water vascular system, which includes sea stars, sea urchins, and sand dollars.

Chordate:

An animal belonging to the phylum Chordata, which includes vertebrates and some invertebrates, characterized by having a notochord at some stage of development.