Beatty, William Lee
(2003)
The Role of Spinose Ornament in Predator Deterrence and Epibiont Colonization: The Bivalve Arcinella, Pinecrest (Pliocene) of Florida.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The spinose shells of the sessile, epifaunal bivalve Arcinella cornuta, from the fossiliferous Pliocene Pinecrest and Caloosahatchee beds of Florida, provide evidence of ecological interactions with both boring predatory gastropods and commensal bivalves. The number, sizes, and positions of borings in A. cornuta were compared to parameters such as size of the valve and density of spines at the boring site to determine to what extent spines influenced the borers. Records of attacks by naticid and muricid gastropods are preserved as borings in the shells of their putative prey. Gastropods can exhibit stereotyped attack patterns and can be highly selective with regard to prey size and boring site in order to optimize net energy return. Although some site and size selectivity was evident, attack strategies toward A. cornuta shifted over time. Spine density at boring sites was negatively correlated with boring frequency, demonstrating that spines hindered predatory attacks. Smaller predators were selective and most often bored at the thinner posterior region of the shell. Larger predators were less selective and most often bored at the lunule; the thickest portion of the shell, but the only area unobstructed by spines. Larger predators apparently accepted longer boring times in order to increase chances at success. Over time, establishing two preferred boring sites enabled predators to optimize their attacks. This direct link between prey morphology and predator adaptation signals that an arms race between these two species may have been underway. A. cornuta shells were also the preferred habitat of boring gastrochaenid bivalves, signaling a shift in the borer's habitat. Some species of the bivalve family Gastrochaenidae dwell in semiendolithic boreholes partially covered by secreted calcareous envelopes or crypts. Gastrochaenids selectively colonized shells of A. cornuta to exploit the feeding currents, armor, and raw materials provided by the host. The distribution of borings and crypts indicates that gastrochaenids colonized and grew within the spines of A. cornuta, orienting their siphons to exploit feeding currents created by the host. As the gastrochaenids matured and outgrew the space available within the spines, they incorporated them into their crypts.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
23 May 2003 |
| Date Type: |
Completion |
| Defense Date: |
7 April 2003 |
| Approval Date: |
23 May 2003 |
| Submission Date: |
6 May 2003 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Geology and Planetary Science |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Arcinella; Arms Race; Boring; Gastrochaenid; Gastropod Predation; Pinecrest |
| Other ID: |
http://etd.library.pitt.edu:80/ETD/available/etd-05062003-191127/, etd-05062003-191127 |
| Date Deposited: |
10 Nov 2011 19:43 |
| Last Modified: |
15 Nov 2016 13:43 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/7799 |
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