The moment of tooth: rate, fate and pattern of Pacific lingcod dentition revealed by pulse-chase

Abstract

Tooth replacement rates of polyphyodont cartilaginous and bony fishes are hard to determine because of a lack of obvious patterning and maintaining specimens long enough to observe replacement. Pulse-chase is a fluorescent technique that differentially colours developing mineralized tissue. We present in situ tooth replacement rate and position data for the oral and pharyngeal detentions of Ophiodon elongatus (Pacific lingcod). We assessed over 10 000 teeth, in 20 fish, and found a daily replacement rate of about two teeth (3.6% of the dentition). The average tooth is in the dental battery for 27 days. The replacement was higher in the lower pharyngeal jaw (LPJ). We found no difference between replacement rates of feeding and non-feeding fish, suggesting feeding was not a driver of tooth replacement. Lingcod teeth have both a size and location fate; smaller teeth at one spot will not grow into larger teeth, even if a large tooth nearby is lost. We also found increased rates of replacement at the posterior of the LPJ relative to the anterior. We propose that lingcod teeth do not migrate in the jaw as they develop; their teeth are fated in size and location, erupting in their functional position.

Continuous tooth replacement: what can teleost fish teach us?

“…Remarkably, Carr et al . (2021) conclude that dental wear in the marine species Ophiodon elongatus does not control the replacement rate and therefore support the hypothesis that replacement is probably maintained by a spatially and temporally driven developmental network. Obviously, such contradictory conclusions do not facilitate answering the question as to what triggers the start of development of a replacement tooth germ.…”

“…They suggest that the oral epithelium retained an initiatory competence throughout life. Carr et al (2021) used the term 'fated' for an individual tooth that is destined to replace a functional tooth at a specific location, i.e. true replacement.…”

“…In the opaleye, the youngest teeth visible beneath the lips require from 22 to 32 days to be replaced and shed (Norris & Prescott, 1959). In several species the replacement cycle revolves around 1 month: an average of 27 days in the Pacific lingcod Ophiodon elongatus [total length (TL) 134–151 mm] (Carr, Summers & Cohen, 2021), around 40 days in the Mexican tetra Astyanax mexicanus (four tooth generations during 163 days of study; Trapani et al ., 2005), and ~4 weeks in the Japanese medaka (Abduweli et al ., 2014).…”

True grit? Comparative anatomy and evolution of gizzards in fishes

“…Thus, gizzards may be a more cost‐efficient way to process food, rather than maintaining both a gut and a dentition. Data in support of the metabolic expense of teeth are currently lacking (Mongle et al, 2020) but they are also central to larger questions in understanding the diversity of tooth replacement modes across vertebrates (Carr et al, 2021; Cohen & Summers, 2023). While data defining the metabolic investment for maintaining a dentition are scarce, current studies in primates suggest that the mineralization of teeth is particularly costly (Smith et al, 2017).…”

Tooth pattern, development, and replacement in the yellow catfish, Pelteobagrus fulvidraco

“…Bemis and Bemis (2015) considered that tooth replacement cycles are influenced by endogenous rhythms, tooth wear, environmental factors, seasonal maturation, egg laying, and so on. However, Carr et al (2021) found that diet and wear are not significantly related to the replacement rate, while mechanical stress and function of teeth may be in Ophiodon elongatus .…”