A New Approach in Examining the Influence of Drugs on Pulsation Rates in Blackworms (Lumbriculus variegatus) - Investigative Laboratory Activity

Oct 15, 2026

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Investigative laboratory activity for college biology students focused on observing, recording, graphing, and analyzing pulsation rates in blackworms (Lumbriculus variegatus). The activity examines how different drugs alter pulsation rates across varying concentrations and introduces two new microscope viewing approaches for the organisms. Students apply scientific inquiry through hypothesis formation, controls, drug concentration calculations, result determination, and week-by-week data analysis.

LanguageEnglish

CategoryExam

FormatPDF

Pages6

Reading Time15 min

AccessFree to download

Abstract

Introduction

Blackworms as a model organism

Circulatory system and pulsation visualization

Procedures

Blackworm care

Worm viewing chambers

A New Approach in Examining the Influence of Drugs on Pulsation Rates in Blackworms (Lumbriculus variegatus). Amy B. Ryan and Nancy L. Elwess* Department of Biological Sciences, State University of New York at Plattsburgh, Plattsburgh, NY 12901 *Corresponding Author: [elwessnl@plattsburgh.edu](elwessnl@plattsburgh.edu) Abstract: This investigative laboratory activity engages students in observing, recording, graphing and analyzing pulsation rates in a commonly used laboratory organism, blackworms. This activity stresses how various drugs can impact the pulsation rate in blackworms at varying concentrations. In addition, we have incorporated two new ways to view the blackworms under the microscope. Key words: Blackworms, pulsation rate, Lumbriculus variegatus, blood vessels, capillary tubes INTRODUCTION Lumbriculus variegatus, or blackworms, are freshwater oligochaetes in phylum Annelida. They are an excellent organism for studying the regeneration of body parts, regulation of reflex activities, bioaccumulation and toxicity of environmental pollutants, and regulation of blood vessel pulsations (Drewes & Fourtner, 1990; Veltz et al., 1996; Bohrer, 2006; Fillafer & Schneider, 2013) . Like other annelids, blackworms have a closed circulatory system (Fig. 1) . Blackworm blood is red, due to a hemoglobin-like pigment called erythrocruorin dissolved in the blood plasma (Jamieson, 1981) . Two major blood vessels, one dorsal and one ventral, extend the length of the blackworm. Pulsations along the dorsal blood vessel (DBV) propel blood through the circulatory system. Because the body wall of the blackworm is transparent, it is possible to visualize the pulsation of the DBV using light microscopy (Lesiuk & Drewes, 1999) . As in humans, the pulsation rate is controlled by the nervous and endocrine systems. Many drugs affect these systems and can have an immediate impact on the pulsation rate, based in part on how quickly they can diffuse through the blackworm’s skin. Due to their simple body plan and ease with which they can be treated with compounds and the subsequent pulsation rate measured, black worms are an excellent model organism for the lab activity described below. Fig.1. A lateral cross section image of a closed circulatory system found in blackworms. Included in this image are major blood vessels and the internal anatomy. The pulsation rates can be determined by counting the pulsation waves at one location on the dorsal blood vessel. Image created by Sophie Kim. This investigative laboratory, designed fora college freshman general biology course, takes a fresh look at a standard blackworm laboratory activity that was first published in 1999 (Lesiuk & Drewes) and again in 2006 (Bohrer, 2006) . Lesiuk and Drewes describe how blackworms can be used as a model system to demonstrate the effects of nicotine and caffeine on blood vessel pulsation and explain how to make the blackworm viewing chambers. Bohrer provides a more in-depth background as to how the Lesiuk and Drewes preparation can be incorporated into the curriculum, by including timelines, materials, methods, and a suggested grading rubric. We have developed two new approaches for viewing the blackworms under the microscope ( Worm Viewing Chambers under Procedures) and have added three drugs to those from the original publications. This activity was done over three weeks. Week 1 (Wk 1) instructed the students on blackworm handling and behavior, as well as determining the pulsation rate under control and experimental conditions (varying caffeine concentration) . Wk1 served as the practice week for procedures done in week 2. Week 2 (Wk 2) was inquiry, with each pair of students exposing their worms to one of three new treatments (cinnamon, celery seed extract, and valerian root) . Wk 2 served asthe application week. Both Wk 1 and Wk 2 stressed laboratory skills, including scientific inquiry, data collection, and microscopy. Scientific inquiry included

FAQs

What learning activities are students expected to perform in this lab?

Students observe, record, graph, and analyze blackworm pulsation rates under control and experimental drug treatments.

How does the lab connect drug effects to pulsation rate changes?

It emphasizes that drugs can impact nervous and endocrine control of pulsations and that diffusion through the blackworm’s skin influences the observed response.

What are the key additions to the original blackworm laboratory setup?

The activity incorporates two new microscope viewing chamber approaches and adds three drugs beyond those used in the earlier publications.

Oct 15, 2026

Upload by Ben