Reduction and variability of trunk spines in the acanthocephalan Corynosoma cetaceum: the role of physical constraints on attachment

Abstract. In this study, we investigated a functional trade-off between trunk attachment and trunk-spine development in the acanthocephalan Corynosoma cetaceum . The worms live attached to the stomach and upper intestine of their cetacean definitive hosts, using the proboscis and spiny foretrunk as the main holdfast; the spiny hindtrunk can also attach by bending ventrally. When the hindtrunk bends, ventral compression generates an anterior fold (AF) and a posterior fold (PF). A morphological analysis based on 7,823 individuals collected from 10 franciscana dolphins, Pontoporia blainvillei , revealed that spines were smaller and more variable in size and occurrence in the folds than on neighboring areas; the growth of fold spines seemed to be inhibited to various degrees. Spines were more reduced in the AF than in the PF, and spines of both folds were more reduced in females than in males. Patterns of reduction appeared to be directly related to the intensity of fold compression associated with hindtrunk bending. Fold compression could induce plastic inhibition of spine growth, and/or could make fold spines maladaptive, spines being reduced by natural selection. Apparently, fold spines neither contact the substrate, nor are they exposed to the environment when the hindtrunk attaches. Therefore, fold spines could have reduced, or lost, their primary function, at least in the definitive host. The reduction and variability of spines in C. cetaceum seem to be unique among Corynosoma species.     

Plasticity-induced growth of dendritic spines by exocytic trafficking from recycling endosomes

Dendritic spines are micron-sized membrane protrusions receiving most excitatory synaptic inputs in the mammalian brain. Spines form and grow during long-term potentiation (LTP) of synaptic strength. However, the source of membrane for spine formation and enlargement is unknown. Here we report that membrane trafficking from recycling endosomes is required for the growth and maintenance of spines. Using live-cell imaging and serial section electron microscopy, we demonstrate that LTP-inducing stimuli promote the mobilization of recycling endosomes and vesicles into spines. Preventing recycling endosomal transport abolishes LTP-induced spine formation. Using a pH-sensitive recycling cargo, we show that exocytosis from recycling endosomes occurs locally in spines, is triggered by activation of synaptic NMDA receptors, and occurs concurrently with spine enlargement. Thus, recycling endosomes provide membrane for activity-dependent spine growth and remodeling, defining a novel membrane trafficking mechanism for spine morphological plasticity and providing a mechanistic link between structural and functional plasticity during LTP.     

Structure and function of clypeasteroid miliary spines (Echinodermata,Echinoides)

Summary Histological and ultrastructural techniques have been used to describe the functional morphology of clypeasteroid miliary spines, with special reference to their supposed mucus-secreting role. Mucus cells were not found in the miliary spines of any members of the Arachnoididae, Fibulariidae, Laganidae, Echinarachniidae, Dendrasteridae, Astriclypeidae, or Mellitidae examined in this study. Only members of the Clypeasteridae have mucus-secreting cells in these spines. Characteristics of the skeleton, ultrastructure of the nervous system, and histology of the musculature and epithelia of the base, shaft and tip are also discussed. Miliary spines have two bands of cilia running along the entire length of opposite sides of the shaft. The geometric packing of cilium-bearing cells in these bands is described for the first time, as is the remarkable form of the sacs found at the tips of dendrasterid, astriclypeid, and mellitid miliary spines. These sacs are definitely not mucous sacs, as previously described, but are balloons of single-celled epithelium internally tethered to the skeletal tip by copious quantities of collagenous connective tissue. Miliary spines prevent obstruction of aboral nutritive and ventilatory ciliary currents caused by substrate particles falling to the test surface during burrowing. They do this in two ways: (1) they help generate ciliary currents that sweep finer material off the test, and (2) they contribute to the formation of a spine canopy that mechanically blocks larger particles from falling between the spines. Members of the Clypeasteridae secrete an interspine mucous tent that traps potentially clogging material. The miliary spine sacs of sand dollars are deformable space-fillers that plug holes between primary spines in the aboral canopy, even as the spines rock on their tubercles to push sand backwards over the test. Allometry of spines from Echinarachnius parma suggests that aboral military spines and club-shaped spines exhibit co-ordinated growth that maintains the aboral canopy throughout post-metamorphic ontogeny, and that aboral spins have an overall lower growth rate than spines on the oral surface.     

The nature and construction of skeletal spines inPocillopora damicornis (Linnaeus)

Extreme variability in the size, shape and spacing of skeletal spines ofPocillopora damicornis has been demonstrated both within single colonies and also between colonies from different environments. Preliminary studies indicated that the majority of spines from branch tips at the apex of the colony display a ‘fasciculate’ growth surface in contrast to partly fasciculate or ‘smooth’ growth surfaces exhibited by spines from branch tips at the base of the colony. No significant differences in the height and width of costal spines from apical and basal branch tips within a single colony were observed, although spines from colonies exposed to strong wave action tended to be significantly shorter and narrower than those from more sheltered environments. Both costal and coenosteal spines from wave-exposed colonies displayed branching and divided extremities while those from sheltered environments consisted of simple cones. Spines develop as an outgrowing of the calicoblastic ectoderm which secretes the skeleton. Growing costal and coenosteal spines are enveloped by a layer of calicoblastic ectoderm which penetrates through mesogloea, aboral gastroderm, coelenteron, oral gastroderm, mesogloea and finally oral ectoderm. Spines within the corallite are surrounded by calicoblastic ectoderm, mesogloea and aboral gastroderm only. A scheme for the growth of the spines is discussed.     

A comparative study of the life style of two Jurassic irregular echinoids

The irregular echinoids Plesiechinus ornatus (Buckman) (Pygasteroida) and Galeropygus agariciformis (Forbes) (Cassiduloida) occur together in beds of the murchisonoe Zone, Bajocian, outcropping in the Cheltenham region of Gloucestershire. These species were largely restricted to different lithofacies within the carbonate shelf environment. Both adopted a hidden mode of life but achieved this by different techniques. Plesiechinus had fairly short spines and strongly muscular podia over the whole corona and was able to cover itself with coarse substrate particles. The oral tubercles are bilaterally symmetrical and are radially arranged. The oral spines are thought to have pulled sediment out from beneath the test, excavating a small depression for it. Galeropygus bore a dense covering of very small spines and its tube feet were differentiated into aboral respiratory podia and oral suckered podia. It had a preferred anterior direction of locomotion and is thought to have buried itself completely by excavating and ploughing into the substrate as it moved forward. Plesiechinus fed using only its lantern and postulated peristomial tube feet, whereas Galeropygus was a continugus sediment swallower and used its phyllode tube feet and peristomal lip spines in transferring particles towards the mouth.     

Attachment structures in Rhizotrochus (Scleractinia): macro‐ to microscopic traits and their evolutionary significance

Marine sessile benthic organisms living on hard substrates have evolved a variety of attachment strategies. Rhizotrochus (Scleractinia, Flabellidae) is a representative azooxanthellate solitary scleractinian coral with a wide geographical distribution and unique attachment structures; it firmly attaches to hard substrates using numerous tube‐like rootlets, which are extended from a corallum wall, whereas most sessile corals are attached by stereome‐reinforced structures at their corallite bases. Detailed morphological and constructional traits of the rootlets themselves, along with their evolutionary significance, have not yet been fully resolved. Growth and developmental processes of spines in Truncatoflabellum and rootlets in Rhizotrochus suggest that these structures are homologous, as they both develop from the growth edges of walls and are formed by transformation of wall structures and their skeletal microstructures possess similar characteristics, such as patterns of rapid accretion and thickening deposits. Taking molecular phylogeny and fossil records of flabellids into consideration, Rhizotrochus evolved from a common free‐living ancestor and invaded hard‐substrate habitats by exploiting rootlets of spines origin, which were adaptive for soft‐substrate environments.     

Internal structure and paleoecology of the lower Permian Uzunbulak reef complex of the Tarim Basin,Northwest China

Summary The internal construction and biotic communities of the Uzunbulak reef of the northwestern Tarim Basin are studied for the first time. The reef was built during the Sakmarian, while the reef substrate and capping beds are of latest Asselian and earliest Artinskian ages, respectively. The reef substrate beds are composed of skeletal and oncoid grainstone. Those fusulinid-dominated skeletal shoals and oncoid banks indicate a high-energy environment and produced local topographic highs on which the reef grew. Reef framework consists mainly of calcisponge bafflestone, calcisponge-Thartharella framestone, and Tubiphytes, Archaeolithoporella and Girvanella boundstones. Calcisponges were the primary frameconstructors that baffled high-energy currents. Archaeolithoporella, Tubiphytes, Girvanella and possibly microbes acted as the primary binders for the boundstone framework. Fusulinids and brachiopods were common reef dwellers. The interreef facies sediments are composed of skeletal-crinoid wackestone-packstone. Most of bioclasts have thick, micritized envelopes. The back-reef facies deposits consist of alternating skeletal packstone to wackestone and black shale. Sea-level fluctuations were probably accountable for the reef growth and demise. Of the reefal dwellers, brachiopods are extraordinarily abundant in Uzunbulak. They are assignable to five distinctive associations, one each from the reef substrate, framework and inter-reef facies, respectively, and two from the reef capping facies. The brachiopods in the substrate beds were mostly attached to hard substrates by a pedicle, while a few species rested on soft substrates by support of halteroid spines. Cementation of the ventral valve on hard substrates characterizes attachment of the reef framework brachiopods. All inter-reef species were anchored into the substratum comprising hard material by a strong pedicle. Back-reef brachiopods dominantly rested on the soft substrates by support of halteroid spines. the framework brachiopods had the strongest wave-resistant capability;those from both substrate and inter-reef facies were moderately capable of withstanding agitation; and the backreef species preferred to live in calmwater, organic-rich muddy environments.     

The effect of cactus spines on light interception and Photosystem II for three sympatric species of Opuntia from the Mojave Desert

Cactus spines reduce herbivory, direct water toward roots and reduce the impacts of high- and low-temperature extremes. Yet, shading of stems by spines reduces incident photosynthetic photon flux density (PFD), photosynthesis and growth. This study compared spinescence, PFD interception, stem temperature, Photosystem II (PSII) photochemistry and xanthophyll pigment composition for three species of cacti from the Mojave Desert, CA. The species vary in spinescence: Opuntia basilaris , which has no central or radial spines; Opuntia erinacea , which is densely covered with spines; and Opuntia phaeacantha , which has an intermediate coverage of spines. The role of spines was tested by removing spines from stems of O. erinacea . PFD interception was similar for both O. basilaris and O. phaeacantha , and about three times that for densely spined O. erinacea ; removal of spines increased incident PFD three-fold. There were no effects of spines on stem temperatures. Steady-state light-response curves of chlorophyll a fluorescence from PSII indicated that ΦPSII, photochemical quenching (qP) and electron flux within PSII were lower, and non-photochemical quenching was higher, for O. erinacea in comparison to the other two species with less spines. After 2 months, qP was higher and electron flux lower, and xanthophyll pigment pool size was higher, for stems from which spines had been removed compared with intact stems. These three species allocate different amounts of biomass to spines, resulting in species-specific PFD interception, PSII photochemistry and xanthophyll pigment pool size, which may help maintain rates of photosynthesis during the hot, dry Mojave Desert summer.     

Morphologie des épines chez les brachiopodes Delthyrididae

Two main types of micro-ornament can be observed in the family Delthyrididae (Brachiopoda, Spiriferidina): capillae (with continuity of the structures from one growth lamella to the next one) and spines (with the appearance of discontinuity). SEM studies of the spines show that, contrary to previous assumption, the cross section is not circular but subquadrangular with a longitudinal groove on top. Each spine is connected in front to the next one so that they give rise to a continuous radial structure. Thus the spine is a local external differentiation of the underlying microfila. Furthermore, the spinose ornament is derived from the capillate ornament. During growth, new fila and spines appear in the grooves and diverge towards the top of adjacent costae, running across several lamellae. When there are few spines, they have a uniform size, but when there are many spines, small spines (issued from newer fila) are juxtaposed with large spines (issued from older fila). The use of micro-ornament in systematics has often been based on misinterpretations; attention is drawn to the fact that the shape of the spine base is not representative of the original shape of the spine but generally resulted from the erosion of the shell. Nevertheless, more detailed studies on spine shape and arrangement offer interesting prospects for classification.     

A Simple Rule for Dendritic Spine and Axonal Bouton Formation Can Account for Cortical Reorganization after Focal Retinal Lesions

Lasting alterations in sensory input trigger massive structural and functional adaptations in cortical networks. The principles governing these experience-dependent changes are, however, poorly understood. Here, we examine whether a simple rule based on the neurons'' need for homeostasis in electrical activity may serve as driving force for cortical reorganization. According to this rule, a neuron creates new spines and boutons when its level of electrical activity is below a homeostatic set-point and decreases the number of spines and boutons when its activity exceeds this set-point. In addition, neurons need a minimum level of activity to form spines and boutons. Spine and bouton formation depends solely on the neuron''s own activity level, and synapses are formed by merging spines and boutons independently of activity. Using a novel computational model, we show that this simple growth rule produces neuron and network changes as observed in the visual cortex after focal retinal lesions. In the model, as in the cortex, the turnover of dendritic spines was increased strongest in the center of the lesion projection zone, while axonal boutons displayed a marked overshoot followed by pruning. Moreover, the decrease in external input was compensated for by the formation of new horizontal connections, which caused a retinotopic remapping. Homeostatic regulation may provide a unifying framework for understanding cortical reorganization, including network repair in degenerative diseases or following focal stroke.     

Structure and development of the ctenial spines on the scales of a teleost fish,the cichlid Cichlasoma nigrofasciatum

Sire, J.‐Y. and Arnulf, I. 2000. Structure and development of the ctenial spines on the scales of a teleost fish, the cichlid Cichlasoma nigrofasciatum. — Acta Zoologica (Stockholm) 81 : 139–158 Numerous teleost species possess ctenoid scales characterized by the presence of ctenial spines arranged in rows (the cteni) along their posterior, free margin. Whilst the morphology and function of the ctenial spines are similar to those of odontodes (extra‐oral teeth), e.g. in armored catfish, their homology is questionable. To address this problem, we have studied ctenial spine development, structure, attachment to a bony support, and replacement with the aim of comparing these features to those described for odontodes. The ctenial spines have been studied in a growth series of the cichlid Cichlasoma nigrofasciatum, using light, scanning and transmission electron microscopy. Ctenial spines are entirely constituted of a collagen matrix. They lack a pulp cavity and, although their distal end can be in contact with the epidermal basal layer cells, they are not covered by an enameloid‐like tissue. They are attached to the scale by means of a narrow strand of unmineralized collagen matrix acting as a ligament and allowing spines to be movable. The ctenial spines develop as prolongations of the external layer of the scale, a woven‐fibroid collagen matrix, and subsequently grow by addition of parallel‐fibred collagen matrix. New ctenial spines are added at the posterior scale border in waves that follow the same rhythm as the deposition of circuli in the anterior region. From the focus region to the scale border, the ctenial spines constitute lines in which only the most posterior ctenial spine is functional. The other spines that are no longer functional are not shed but resorbed from the top, and their attachment region mineralizes and thickens by deposition of new material. The remnants of spines constitute the main part of the superficial layer of the scale in which anchoring bundles attach; this region is covered afterwards by the limiting layer, a tissue devoid of collagen fibrils. Because of their tooth‐like morphology (shape and size), their posterior orientation and their attachment to the scale surface, the ctenial spines resemble odontodes. Moreover, both elements perform a similar hydrodynamic function. Nevertheless, the structure and development of the ctenial spines differ completely from those of odontodes and consequently, they cannot be considered homologous elements. Ctenial spines and odontodes in teleosts provide us with a beautiful example of homoplasy; they share shape and function, but have a different origin as evidenced by their different structure and process of development.     

Functional morphology of chonetidine (Brachiopoda) spines: biomechanical tests of a potential key innovation

Chonetidine brachiopods were a significant component of Paleozoic marine life; chonetidines experienced a major adaptive radiation during the Late Silurian and Early Devonian. The Chonetidina clade is united by the presence of spines on the hingeline but the function of these spines has not been clearly demonstrated. The present study performs a biomechanical experiment, using specimens of Neochonetes granulifera with and without artificial spines in a recirculating flume, to test if the spines may have inhibited entrainment in higher energy settings. Specimens with spines were less likely to be overturned or transported than those without spines, and were overturned or transported at significantly higher velocities than specimens without spines. Performance improved with the addition of another pair of spines. In addition, spinose specimens reoriented such that their commissures faced upstream. The results suggest that chonetidines could have survived in higher-energy environments, even if the brachiopods were not physically attached to the substrate. As such, it is functionally plausible that the evolution of hinge-spines may have possibly facilitated the adaptive radiation of the clade by enabling chonetidines to inhabit previously unoccupied habitats.     

Spine skeleton morphogenesis during regeneration in clypeasteroid and camarodont sea urchins

The process of skeleton morphogenesis is described for broken and totally removed spines in clypeasteroid (hollow spine) and camarodont (solid spine) sea urchins. Spine regeneration after total spine removal is completed in 40–45 days in clypeasteroids and in 60–70 days in camarodont sea urchins. Along with common stages of formation of longitudinal ribs in both hollow and solid spines, fundamental differences were found between the initial stages of reparative growth of the spine shaft. The spine shaft is formed from a single median process in clypeasteroids and from many simultaneously growing processes in camarodont sea urchins. Reparative morphogenesis of totally removed and partly broken spines in clypeasteroid sea urchins and totally removed spines in camarodont sea urchins leads to the formation of a skeletal structure identical to the intact spine. However, during the regeneration of broken camarodont spines, lateral growth is markedly retarded. As a result, the regenerated part of the spine shaft has a smaller diameter when the initial spine length is achieved. A hypothesis is proposed on a paedomorphic origin of spines in the clypeasteroid sea urchins on the basis of the juvenile stage of definitive spines in the camarodont sea urchins.     

Age estimation and validation for South Pacific albacore Thunnus alalunga

Validated estimates of age are presented for albacore Thunnus alalunga, sampled from a large part of the south‐western Pacific Ocean, based on counts of annual opaque growth zones from transverse sections of otoliths. Counts of daily increments were used to estimate the location of the first opaque growth zone, which was completed before the first assumed birthday. The periodicity of opaque zones was estimated by marginal increment analysis and an oxytetracycline mark–recapture experiment. Both validation methods indicated that opaque zones formed over the austral summer and were completed by autumn to winter (April to August). The direct comparison of age estimates obtained from otoliths and dorsal‐fin spines of the same fish indicated bias, which was assumed to be due to poor increment clarity and resorption of early growth zones in spines, resulting in imprecise age estimates. As such, age estimates from otoliths are considered to be more accurate than those from spines for T. alalunga. This is consistent with results for a growing number of tropical and temperate tuna Thunnini species. It is recommend that validated counts of annual growth zones from sectioned otoliths is used as the preferred method for estimating age‐based parameters for assessment and management advice for these important stocks.     

Geometric shell growth and mode of life of a Devonian chonetoidean brachiopod

Morphological and statistical analysis of the chonetoid species Kentronetes variabilis from the Lower Devonian (Lochkovian) of the Argentine Precordillera demonstrate ontogenetic changes and allometric relationships between characters. A special study was made of spine distribution, morphology, and growth, compared to valve growth. The first, inner, developed spines (pairs 1–1'and 2–2') continued to grow after development of the following outer pairs. The spacing of spines, their diameter, and the density of growth rings vary from beak to posterolateral margins following a specific 2ⁿ geometric growth factor, compared to the regular, almost linear growth of the valves, attested by growth lines. The linear growth rate of outer spines (pairs 3–3'and 4–4') can be 6–8 times more rapid than that of the shell on the valve margin. Ontogenetic changes in spine morphology are interpreted as a response to changes in the mode of life.     

Dynamic microtubules promote synaptic NMDA receptor-dependent spine enlargement

Most excitatory synaptic terminals in the brain impinge on dendritic spines. We and others have recently shown that dynamic microtubules (MTs) enter spines from the dendritic shaft. However, a direct role for MTs in long-lasting spine plasticity has yet to be demonstrated and it remains unclear whether MT-spine invasions are directly influenced by synaptic activity. Lasting changes in spine morphology and synaptic strength can be triggered by activation of synaptic NMDA receptors (NMDARs) and are associated with learning and memory processes. To determine whether MTs are involved in NMDAR-dependent spine plasticity, we imaged MT dynamics and spine morphology in live mouse hippocampal pyramidal neurons before and after acute activation of synaptic NMDARs. Synaptic NMDAR activation promoted MT-spine invasions and lasting increases in spine size, with invaded spines exhibiting significantly faster and more growth than non-invaded spines. Even individual MT invasions triggered rapid increases in spine size that persisted longer following NMDAR activation. Inhibition of either NMDARs or dynamic MTs blocked NMDAR-dependent spine growth. Together these results demonstrate for the first time that MT-spine invasions are positively regulated by signaling through synaptic NMDARs, and contribute to long-lasting structural changes in targeted spines.     

Polyribosomes redistribute from dendritic shafts into spines with enlarged synapses during LTP in developing rat hippocampal slices

The presence of polyribosomes in dendritic spines suggests a potential involvement of local protein synthesis in the modification of synapses. Dendritic spine and synapse ultrastructure were compared after low-frequency control or tetanic stimulation in hippocampal slices from postnatal day (P)15 rats. The percentage of spines containing polyribosomes increased from 12% +/- 4% after control stimulation to 39% +/- 4% after tetanic stimulation, with a commensurate loss of polyribosomes from dendritic shafts at 2 hr posttetanus. Postsynaptic densities on spines containing polyribosomes were larger after tetanic stimulation. Local protein synthesis might therefore serve to stabilize stimulation-induced growth of the postsynaptic density. Furthermore, coincident polyribosomes and synapse enlargement might indicate spines that are expressing long-term potentiation induced by tetanic stimulation.     

Post-embryonic development of the Furongian (late Cambrian) trilobite Tsinania canens: implications for life mode and phylogeny

SUMMARY The current concept of the order Asaphida was proposed to accommodate some Cambrian and Ordovician trilobite clades that are characterized by the possession of a ventral median suture. The family Tsinaniidae was recently suggested to be a member of the order Asaphida on the basis of its close morphological similarity to Asaphidae. Postembryonic development of the tsinaniid trilobite, Tsinania canens , from the Furongian (late Cambrian) Hwajeol Formation of Korea, reveals that this trilobite had an adult-like protaspis. Notable morphological changes with growth comprise the effacement of dorsal furrows, sudden degeneration of pygidial spines, regression of genal spines, and loss of a triangular rostral plate to form a ventral median suture. Programmed cell death may be responsible for degenerating the pygidial and genal spines during ontogeny. Morphological changes with growth, such as the loss of pygidial spines, modification of pleural tips, and effacement of dorsal furrows, suggest that T. canens changed its life mode during ontogeny from benthic crawling to infaunal. The protaspid morphology and the immature morphology of T. canens retaining genal and pygidial spines suggest that tsinaniids bear a close affinity to leiostegioids of the order Corynexochida. Accordingly, development of a ventral median suture in T. canens demonstrates that the ventral median suture could have evolved polyphyletically, and thus the current concept of the order Asaphida needs to be revised.     

Extreme cyclomorphosis in Daphnia lumholtzi

1. Daphnia lumholtzi, not previously reported in North America, was found in a small reservoir in East Texas in January, 1991, This species possesses extremely long spines and large fornices; an allometric study was performed to detect any temporal differences in specific growth rates of the spines relative to the body. 2. In nature, mature females attained 1.8mm body length, excluding spines, but when the head and tail spines are included, the total length reached a maximum of 5.6mm. 3. Differences in the growth patterns of the head spine and the tail spine relative to the body existed for D. lumholtzi from January to March 1991. Both the head and the tail spines grew at a faster rate than the body during all 3 months although the rates varied between them. The results contradict the invertebrate predation hypothesis (Dodson, 1974) in that D. lumholtzi's head and tail spines continue to grow during adulthood instead of stopping after the juvenile instars. 4. The head spines grew at a constant allometric rate over time while the tail spine grew faster as the temperature increased. Both varied significantly in length over the 3 months, with animals having the shortest spines in February and the longest in March.     

Froghood: Postmetamorphic development of the rock river frog Thoropa miliaris (Spix, 1824) (Anura,Cycloramphidae)

Thoropa miliaris is a frog species endemic to the Brazilian Atlantic Rainforest, inhabiting wet rocky habitats. Males of this species present nuptial excrescences, which are keratinized spines on the surface of some fingers and internal metacarpal tubercles. Although these spines are usually associated with male adulthood, no details of their development are available. To investigate the sequence of spines' appearance, we correlated the number of spines with size and age, which was estimated by skeletochronology. We studied individuals collected from Rio de Janeiro, Brazil. There was significant correlation between size of individuals and number of spines and between age and number of spines in the callosities. The first spines appeared in metacarpal–phalangeal articulation of finger II, when specimens were 1 year old. The estimated growth curve did not show stabilization at any age. We considered the degree of development of the nuptial excrescences as a proxy for sexual maturity and so individuals may already be sexually active by 1 year of age. Estimated longevity of T. miliaris is similar to that estimated for other tropical species of frogs. Although growth in anuran species is considered to be undetermined, in T. miliaris, it seems to fit either undetermined or determined models.