Instructor Notes (Ecdysozoans)

Animals: Ecdysozoans

Overview

This module focuses on the Ecdysozoans, which include key animal groups known for their process of molting. All dissections for the semester are introduced in the Folio Hurricane Dissection Module, with a Dissection Quiz (Assessment #10) due by 11:59 PM on Friday, 11/15.

Ecdysozoans Background Lecture

Key Terms

To understand the concepts presented in this module, familiarity with the following terminology is essential:

  • Ecdysis: This refers to the process of molting, specifically the shedding of a cuticle. It is a common characteristic among ecdysozoans.
  • Cuticle: The cuticle serves as the outer covering or exoskeleton of organisms within the Ecdysozoa group.
  • Oral Papilla: These are slime glands found in velvet worms, capable of ejecting slime that helps in capturing prey.
  • Pseudocoelomate: This term describes an organism that possesses a body cavity lacking a complete tissue layer known as the peritoneum.
  • Metamorphosis: This term refers to the significant change in form or structure that organisms undergo as they transition from larval to adult stages, often involving several intermediate steps.
  • Chitin: A durable, water-resistant polysaccharide that comprises the exoskeleton of arthropods, providing both protection and structure.

Characteristics of Ecdysozoans

Ecdysozoans are classified as protostomes, a group characterized by their developmental process where the blastopore (the first opening that forms) develops into the mouth of the digestive system. The ecdysozoan lineages examined in this lab include:

  1. Nematodes (roundworms)
  2. Onychophorans (velvet worms)
  3. Arthropods (including horseshoe crabs, crustaceans, ticks, mites, and insects)
Developmental Features

The developmental traits of ecdysozoans include:

  • Cleavage: Characteristic of protostome development, specifically about how early stages of cell