Graduation Date
Spring 2019
Document Type
Thesis
Program
Master of Science degree with a major in Biology
Committee Chair Name
Paul Bourdeau
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Edward Metz
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
John Reiss
Third Committee Member Affiliation
HSU Faculty or Staff
Fourth Committee Member Name
Brian Tissot
Fourth Committee Member Affiliation
HSU Faculty or Staff
Keywords
Pisaster, Aboral spines, Morphology, Intertidal, Functional morphology, Intraspecific variation
Subject Categories
Biology
Abstract
Rocky intertidal zones are highly dynamic environments that exhibit substantial spatial and temporal variation in abiotic conditions, which can drive body form variation and energy allocation within calcifying species. Wave exposure, specifically, has been shown to be a significant driver of skeletal and structural morphology in organisms including gastropods, bivalves, and sponges. Many of such organisms, from sponges to echinoderms, rely on calcium carbonate for structural support and protection.
In the phylum Echinodermata (named for possessing a ‘spiny skin’), research on the form and function of calcium carbonate spines is largely relegated to Class Echinodea (e.g., urchins and sand dollars) and superorders Spinulosacea and Valvatacea within Class Asteroidea (sea stars). Few studies have provided morphological descriptions and functional hypotheses for spines in the Superorder Forcipulatida within Asteroidea. Here, I examine aboral spine morphology and variation in the forcipulate seastar, Pisaster ochraceus, a habitat generalist in rocky intertidal zones of the eastern North Pacific. I found that aboral spine density was significantly higher in sea stars in more physically-harsh bench and boulder field habitats compared to more physically-benign habitats like protected embayments. I also found specific aboral spine morphotypes that were associated with specific habitats; sea stars in protected embayments had spines that were upright and columnar, whereas bench and boulder field sea stars had shorter, convex spines. I hypothesize that dense, convex aboral spines have the potential to function as protection for the aboral surface of sea stars in habitats exposed to the combined stresses of high wave action and sediment load, but future studies are necessary to fully elucidate function.
Citation Style
APA
Recommended Citation
Jones, Angela Jordane, "Analysis of aboral spine variation in the forcipulate sea star, Pisaster ochraceus (Brandt 1835)" (2019). Cal Poly Humboldt theses and projects. 257.
https://digitalcommons.humboldt.edu/etd/257