Functional adaptation of spiriferide brachiopod morphology

Abstract

It has been suggested that spiriferide morphologies have evolved to adapt to a variety of environmental conditions. Through a computational fluid dynamics approach, we examined how the spiriferide original form was optimized for a lotic condition, specifically addressing the functionalization of the Devonian spiriferide brachiopod Paraspirifer bownockeri to generate passive feeding flows. The results using four models, each of which differed in the development of the spiriferide shell depression, i.e. sulcus, showed that a deeper sulcus functions to create strong spiral flows so as to align on the feeding organ inside the shell. Among the sulcus‐developed models, only the mimic of the natural form could generate comparative slow flows with a stable inflow area. The fossil record of spiriferides shows a morphological trade‐off between the development of the sulcus and wing form. We concluded that spiriferide shells with such a morphological combination evolved to produce various feeding strategies, resulting in diversification.

Pelagic or benthic? Mode of life of the remopleuridid trilobite Hypodicranotus striatulus

“…The CFD simulation methods used here have been fully described in previous reports by our group (Shiino et al 2009(Shiino et al , 2012Shiino & Kuwazuru 2010, 2011a. The methodology is briefly described below.…”

“…The simulation was performed using the commercial computational fluid dynamics code SCRYU/Tetra 9.0 (Software Cradle Co., Ltd., Tokyo, Japan), which employs the finite-volume method (e.g., Adkins & Yan 2006, Shiino et al 2009). To implement a three-dimensional model of Hypodicranotus for analysis in the CFD simulation, we constructed a polycarbonate exoskeletal replica using the vacuum-forming method (Shiino et al 2009, Shiino 2010) and obtained sequential cross-sectional images of the replica using an SMX-225CT microfocus X-ray CT system (Shimadzu Corporation, Tokyo, Japan). Subsequently, the volumetric data were translated into surface morphological data in • C -hypostome (MCZ-100987).…”

Theoretical approach to the functional optimisation of spiriferide brachiopod shell: Optimum morphology of sulcus

“…It has been suggested that the shell of Paraspirifer passively generated inflow and outflow for feeding and respiration (Shiino et al, 2009;Shiino, 2010;Shiino and Kuwazuru, 2010b). To generate passive flow, the sulcus must generate a pressure difference between the sulcus and lateral gapes, with the higher pressure at the sulcus (Shiino et al, 2009).…”

“…Almost all animal forms are apparently formulated in a way that makes it possible to perform requisite physiological and ecological tasks. In light of the fact that the expression of a function is nonlinear with a morphological change (Koehl, 1996;Shiino and Kuwazuru, 2010b), it is necessary to quantitatively estimate how differences in morphological characteristics affect biological performance and how morphological plasticity allows for the maintenance of that performance.…”

Stealth Effect of Red Shell in Laqueus rubellus (Brachiopoda, Terebratulida) on the Sea Bottom: An Evolutionary Insight into the Prey-Predator Interaction

“…Spiriferinids, which were one of the most thrived brachiopod groups and showed no indications of colour [36], became extinct soon after the diversification of the macropredators even though they possessed certain morphologies that are considered to be exquisite adaptations for feeding system [37][38][39][40][41]. On the other hand, terebratulids did not become extinct but began to diversify and persisted to the modern era [42].…”