Young Spiders Research Articles

The Process of Becoming a “Spider-Man”

Spider-Man gets his special powers from a spider bite. Real spider males do not have special powers, but they do have a specialized organ that female spiders do not have. It is called the bulbus organ, and it is needed for mating and thus really important. It is fascinating that the bulbus organ is absent in young spiders and has to develop inside of tiny appendages on the front of the spider, called pedipalps. The way organs develop inside already functioning body parts has puzzled researchers for years. Recently, scientists have found that the bulbus organ develops from a small set of cells, which are present early during the spider’s development. Interestingly, during the development of the bulbus organ, other structures in the pedipalp are totally rebuilt from a mysterious material. Such processes usually only occur during metamorphosis in insects. This is the first example of a metamorphosis-like process happening in a species that does not have metamorphosis. So, maybe spiders have special powers after all!

Growing tiny eyes: How juvenile jumping spiders retain high visual performance in the face of size limitations and developmental constraints

Adult jumping spiders are known for their extraordinary eyesight and complex, visually guided behaviors, including elaborate communicatory displays, navigational abilities, and prey-specific predatory strategies. Juvenile spiders also exhibit many of these behaviors, yet their visual systems are many times smaller. How do juveniles retain high visually guided performance despite severe size constraints on their visual systems? We investigated developmental changes in eye morphology and visual function in the jumping spider Phidippus audax using morphology, histology, ophthalmoscopy, and optical measurements. We find that juvenile spiders have proportionally larger lenses in relation to their body size than adults. This should alleviate some of the costs of small body size on visual function. However, photoreceptor number in the anterior lateral eyes (ALE) remains constant from early development onward, consistent with a developmental constraint on photoreceptor differentiation. To accommodate these photoreceptors within the diminutive volume of the spiderling cephalothorax, ALE rhabdoms in early life stages are more tightly packed and significantly smaller in diameter and length, properties that expand across development. Lens focal lengths increase as eyes and retinas grow, resulting in a remarkable maintenance of ALE spatial acuity and field-of-view across life stages. However, this maintenance of acuity comes at a sensitivity cost given the small rhabdomal volumes required by space constraints early in life. Taken together, our results indicate that young jumping spiders have eyes already equipped for high acuity vision, but these young spiders may struggle to perform visually demanding behaviors in low-light environments, a notion that warrants further testing.

Protein Content in Silken Webs of Cellar Spiders (Family-Pholcidae): Effect of Habitat and Senescence

Different class of spiders spin silk to construct different web architectures. Spider’s silk is an extraordinary semi-crystalline biopolymer, which is highly tough and elastic. In the present study we have assessed the total protein content in spider webs produced by young and old cellar spiders (family pholcidae) inhabiting different environments. Data revealed that the total protein content in webs spun by young spiders was higher compared to old spiders of the same spider family. Also, the total protein content in webs spun by garden spiders was significantly higher compared to house spiders of the same spider family.

Just Itzy by Lana Krumwiede (review)

Reviewed by: Just Itzy by Lana Krumwiede Jeannette Hulick Krumwiede, Lana Just Itzy; illus. by Greg Pizzoli. Candlewick, 2015 34p ISBN 978-0-7636-5811-3 $15.99 R 5-7 yrs Young spider Itzy Bitzy is looking forward to his first day of “spindergarten,” but he’s unsuccessful at spinning class, scaring a girl on a tuffet and getting temporarily consumed by an old lady. He ditches his third spinning attempt in order to climb up a waterspout in response to cries for help, finding his big brother, Gutzy, is afraid to climb back down the tall spout. Itzy shows him the way down the web-ladders he has spun, and the pair safely descends, where Itzy discovers another reason to be proud: his third web attempt has actually netted him two flies. Krumwiede spins a solid and entertaining backstory for the itsy bitsy protagonist, and the book cleverly and humorously incorporates various spider-themed nursery songs/ rhymes (“Crikey crickets! The old lady swallowed the fly! Itzy didn’t know why she swallowed the fly”). Kids will be tickled by the rhyme/song connections and by some of the specifics of Itzy’s world. Greens, golds, and robin’s egg tones feature prominently in Pizzoli’s sunny illustrations (rendered with pencil, India ink, Plaka paint, and Photoshop), and slightly fuzzy edges give a casual, childlike look to the [End Page 453] art. The endearing, bespectacled Itzy sports a red ball cap and wears black sneakers on two of his eight legs (the other six are used as arms), and he and the rest of the spider characters are more adorable than alarming. Pair this with Cronin’s Diary of a Spider (BCCB 10/05), share it as a light-hearted addition to a bug-themed unit, or use it as a springboard to a nursery rhyme–themed creative writing project. Copyright © 2015 The Board of Trustees of the University of Illinois

Pavouci (Araneida) Lesního lomu (Brno-Hády)

Spiders were collected in a partially reclaimed limestone quarry in the stone massif Hády at Brno. Collections were performed utilizing pitfall traps in 8 areas (4 lines at quarry terraces, 2 lines in the reclaimed areas, and 2 lines in the immediate vicinity of the quarry) in 2008. In total 67 species were identified from the total number of 1357 specimens determined. In total 1010 specimens were young spiders. Of all the species three are among the vulnerable (Sitticus penicillatus, Dysdera ninnii, and Haplodrassus dalmatensis) and one species is endangered (Haplodrassus minor). The species belong to total number of 16 families. The largest proportion of species belongs to the species that dwelling in thermophyticum (43%) and mesophyticum (43%). From the relict perspective, a higher number of relic species of type 1 (RI – 24%) and relic species (R – 38%) occurred within the observed area. Majority of spiders belong to the species preferring natural habitats (50%) or seminatural habitats (34%).

Do social spiders cooperate in predator defense and foraging without a web?

Nearly all social spiders spin prey-capture webs, and many of the benefits proposed for sociality in spiders, such as cooperative prey capture and reduced silk costs, appear to depend on a mutually shared web. The social huntsman spider, Delena cancerides (Sparassidae), forms colonies under bark with no capture web, yet these spiders remain in tightly associated, long-lasting groups. To investigate how the absence of the web may or may not constrain social evolution in spiders, we observed D. cancerides colonies in the field and laboratory for possible cooperative defense and foraging benefits. We observed spiders’ responses to three types of potential predators and to prey that were introduced into retreats. We recorded all natural prey capture over 447 h both inside and outside the retreats of field colonies. The colony’s sole adult female was the primary defender of the colony and captured most prey introduced into the retreat. She shared prey with younger juveniles about half the time but never with older subadults. Spiders of all ages individually captured and consumed the vast majority of prey outside the retreat. Young spiders benefited directly from maternal defense and prey sharing in the retreat. However, active cooperation was rare, and older spiders gained no foraging benefit by remaining in their natal colony. D. cancerides does not share many of the benefits of group living described in other web-building social spiders. We discuss other reasons why this species has evolved group living.

Ontogeny repeats phylogeny in Steatoda and Latrodectus spiders

Web designs of young spiders are often less derived than those of older conspecific individuals. This study tested whether this “ontogeny repeats phylogeny” pattern occurs in two species of Latrodectus and two species of the closely related genus Steatoda. This pattern was assumed to occur in a recent study of a third Latrodectus species, L. geometricus, which attempted to deduce a probable evolutionary derivation of gum-foot webs of theridiids on the basis of ontogenetic changes. We found the same basic ontogeny repeats phylogeny ontogenetic pattern in all four species, suggesting that the previous suppositions were justified. As expected, the webs of the young instars of the two Latrodectus species were more similar than those of the adults, and were more similar to those of young than to those of adults of L. geometricus. One apparently derived trait of L. mirabilis, attaching prey remains as camouflage for the spider in the central portion of the web, did not change during ontogeny, and was present in even the webs of first-instar spiderlings. Field observations of L. mirabilis suggest that the ontogenetic change from light to darker abdominal color patterns that occurs in many Latrodectus species may result from changes in selection for camouflage associated with ontogenetic changes in web designs and the spiders' resting sites. The webs of Steatoda also fit the ontogenetic pattern: at least some ontogenetic changes in both species involved younger spiders having less derived traits than those of adults. The webs of young Steatoda spiders were more derived in some respects than those of the early instars of Latrodectus.

Effects of web chemical signatures on intraspecific recognition in a subsocial spider, Coelotes terrestris (Araneae)

For web-building spiders, a current hypothesis states that silk structure is involved in intraspecific communication, and could play a major role in regulating social relations. To test this hypothesis, we studied a subsocial spider, Coelotes terrestris (Araneae). During their lifetime, individuals of this species successively experience a social period (parental female and young stages, from hatching to dispersal) and a solitary period (postdispersal young to adult stage). We therefore expected the link between an individual and its web to change depending on whether it was in its subsocial or solitary period. We conducted two complementary studies. Behavioural tests showed that the webs of incubating females were attractive to mated females and the webs of parental females repelled virgin spiders. Dispersal of young spiders was accompanied by characteristic changes in the chemical components of the mother's web. Chromatographic analyses of individual webs revealed the presence of 48 different compounds. The components were alcohol, fatty acids and long-chain aliphatic hydrocarbons. Quantitative as well as qualitative changes in chemical profiles correlated strongly with the physiological state of the spiders that made them. Bioassays showed that the spatial distribution of the spider was influenced by these chemical compounds.

Fauna de aranhas (Arachnida, Araneae) em diferentes estágios do cultivo do arroz irrigado em Cachoeirinha, RS, Brasil

Com a intenção de conhecer a diversidade da araneofauna relacionada à cultura do arroz, foi realizado um inventário deste agroecossistema ainda pouco estudado em sua biodiversidade. Foram realizadas 17 amostragens na Estação Experimental do Arroz (EEA), do Instituto Rio Grandense do Arroz (IRGA), Cachoeirinha, RS (50º58'21"W; 29º55'30"S) entre outubro de 2004 e junho de 2005, em três períodos: antes do arroz ser semeado, durante o desenvolvimento do arroz e após a colheita. As coletas foram efetuadas no período matinal utilizando rede-de-varredura (35 cm de diâmetro), 50 golpes em cada um dos quatro transectos por amostragem. Coletou-se um total de 918 aranhas distribuídas em 14 famílias, com predomínio de Araneidae, Anyphaenidae, Oxyopidae e Tetragnathidae. Entre os indivíduos adultos, foram determinadas 38 morfoespécies, as mais abundantes Alpaida veniliae (Keyserling, 1865), Tetragnatha nitens (Audouin, 1826), Ashtabula sp.1 e Tetragnatha aff. jaculator, as quatro juntas com mais de 45% dos espécimes adultos coletados. Dos estimadores de riqueza de espécies utilizados, o que mais se aproximou da riqueza observada foi Chao 1; segundo este, 87,4% das espécies potencialmente presentes foram amostradas. Os resultados demonstraram que tanto abundância como riqueza tiveram a tendência ao crescimento, acompanhando o desenvolvimento da lavoura de arroz. Uma constante colonização no hábitat foi constatada dado o alto número de aranhas jovens encontradas em todos os períodos. Não foram encontradas diferenças significativas para a correlação entre dados abióticos (temperatura e pluviosidade) com a abundância e a riqueza, exceto pluviosidade vs. riqueza. Entre os grupos funcionais, houve o predomínio das caçadoras emboscadoras, seguido das construtoras de teias orbiculares. A análise de similaridade (ANOSIM) encontrou diferenças significativas entre a fauna dos três períodos avaliados. Assim, a perturbação na forma como o arroz é semeado e colhido altera a estrutura ambiental brutalmente, conduzindo a uma mudança na diversidade de aranhas em termos de riqueza e composição de espécies. Os resultados sugerem a importância de estudos da biodiversidade nos agroecossistemas.

Alternative predatory tactics in a juvenile jumping spider

The hunting behavior of juvenile Yllenus arenarius Menge 1868 in their first week after leaving sub-sand nests was studied. The spiders were tested with prey that can effectively escape (Homoptera) and prey that are not capable of efficient escape (Thysanoptera and larvae of Lepidoptera) in order to assess the complexity of young spiders' hunting tactics. Numerous differences were found in the mode of catching the prey, which indicate that the spiders possess a conditional hunting strategy. The strategy is expressed in: direction of approach, speed of approach, distance of attack and other prey-specific behaviors. The results strongly suggest the pre-programmed background of both the observed behaviors and sensitivity towards certain prey characteristics that enabled prey identification.

Social facilitation of synchronized molting behavior in the spider amaurobius ferox (Araneae, Amaurobiidae)

During the social period, molting behavior of the young spider, Amaurobius ferox, is highly synchronized within the clutch. Result of the experimental study suggests that social facilitation among group members increased the synchronization. The duration of the molting period of grouped spiderlings was significantly shorter than that of individually isolated spiderlings. Involving the particular maternal strategy in food supply, this phenomenon might have adaptive values in the maintenance of mutual tolerance among the siblings by decreasing the interindividual difference in development and in the avoidance of cannibalism on molting individuals. This probably will also serve to make the peaceful collective behaviors of the spiderlings in matriphagy and cooperative prey capture during their social period.

Relationships among food and contact signals in experimental group-living young of tegenaria atrica

Relationships between the quantity of diet, and group vs. individual rearing toward ontogenesis on degree of cannibalism and cuticular lipid profile of young Tegenaria atrica Araneae, Agelenidae were studied. Ad libitum diet increases the development rate and decreases cannibalism between conspecifics compared to a reduced diet. Individually reared young on the two diets showed no quantitative differences in cuticular lipid profile, but differences were observed in individual vs. group rearing modes. The ad libitum-fed grouped young spiders had notably increased quantities of palmitic acid, 13,17-,11,17-, and 9,17-dimethylhentriacontane, methyl oleate, and n-heptatriacontane over the reduced diet, cannibalistic group. Arch. Copyright 1999 Wiley-Liss, Inc.

Preliminary electrophysiological study of the contact chemoreceptors in a spider

During the first stages of their life, young spiders of the species Tegenaria atrica, show behavioural changes that lead them from eusocial groups (5–20 days old) to a solitary life (40 days old). This change is paralleled by an increase in their number of contact chemoreceptors, previously shown to be used during social interactions. We have examined whether these chemoreceptors exhibit functional changes using morphological and electrophysiological techniques. Our results indicate that such changes do not occur at the level of the chemoreceptors, thus suggesting that this behavioural shift has another physiological ground.

A preliminary study of development in twoLatrodectusspecies (Araneae: Theridiidae)

Young spiders of two New Zealand Latrodectus species were reared to maturity. Considerable variability in growth rate, instar length, relative size, colouration, and patterning was observed both intraspecifically and interspecifically. In general, successive instars increased in length. In both species males matured in 4 moults and lived for only 4-10 weeks, whereas females matured in 6 moults and often lived for 2 years.

Quantitative analysis of orb web patterns in four species of spiders.

The orb webs of the four species Araneus pima (species nova), Araneus diadematus (Clerck), Argiope aurantia (Lucas), and Neoscona domiciliorum (Hentz) built under controlled laboratory conditions were compared and evaluated quantitatively at two different points in the life cycle in regard to size, regularity, shape, and fine structure. Orb webs of two species from one genus can be distinguished, but are more alike than webs from different genera. Mature spiders built highly specific webs, a fact which may play a role in species isolation during courtship. In adults, web measures correlated in size with the spiders' taxon; young spiders' web size measurements corresponded rather to their body weight or leg length. A web's regularity seemed to be closely related to age. Adult and young spiders built oval-shaped webs with eccentric hubs. Mesh width was correlated with leg length at both age levels. Web data support the likelihood of a monophyletic evolution of the four species.

Ecological studies of Pirata subpiraticus (BÖESENBERG et STRAND) (Araneae: Lycosidae) II

The life history of Pirata subpiraticus (BÖS. et STR.), was one of the major spiders in East Japan paddy fields, was examined under laboratory conditions.The young spiders that dispersed from the mother's back were reared until maturity, provided the adults of Dorosophira melanogaster and Psilopa spp. as preys, at a constant temperature of about 25°C with 10 hours of daylight.The spiders of the summer generation moulted 5 to 7 times and required an average of 62.7±13.1 days to mature, but the winter nymphs which were collected from paddy fields in October moulted 8 times and required 160.0±8.3 days under the same rearing condition (Table 1). The cause of the significant difference of developmental periods between both generations was not clear. But, this difference may suggest the diapause of winter nymphs of P. subpiraticus that induced by the exposure of the mothers or the eggs to low temperature and short daylength.The carapace widths of the nymphs were measured after each moulting of the winter generation (Table 2). As the carapace widths overlapped between some instars it was impossible to decide the instar by the measurement of the carapace width.The daily food consumption in the immature stages of this species was examined in the summer generation. High predation appeared in the second to forth day after moulting in all instars (Fig. 1). Total food consumptions in each instar increased with advance of the stage, and an average of about 40 flies were killed in the last instar.The daily food consumption of adult females showed 3 peaks occurring after dispersal of the young spiders from the mother's back (Fig. 2 and 3). The peak of food consumption after copulation, however, did not appear when the females mated just after the peak of post-moulting. In cases where other preys than flies were provided, the daily food consumption of these spiders also are described (Table 3-5).

The dispersal of young post-larval bivalve molluscs by byssus threads

NEW observations, both in the marine environment and in the laboratory, indicate that the byssus in young post-larval bivalves has a hitherto unsuspected function—that of dispersal. The method of transport is analogous to the gossamer flight of young spiders. In the laboratory, small scale currents will induce the secretion of what seems to be a single long thread which, by increasing the viscous drag exerted on the young bivalves, enables them to be carried along on relatively small currents. The threads, which stain readily in Alcian blue (a stain selective for acid mucopolysaccharides) are typically long compared with the length scale of the animal itself: for instance an Abra 1 mm long can produce a 2–4-µm diameter thread of length greater than 3 cm. This mechanism, which we term byssus drifting, is functional from the late pediveliger stage up to at least 2.5 mm size in some species, and it has been found to be present in the 20 species tested so far and listed in Table 1 (a functional byssus has not been reported previously1 in post-larval bivalves of those genera marked with an asterisk).

Ecological Energetics of the Spider Tarentula kochi (Araneae: Lycosidae)1

Tarentula kochi Keyserling had a 2-year life cycle and 2 populations which matured in alternate years and utilized 2 size classes of prey. The spiders had 12 instars, and each was 35–40 days long in the field at a temperature of 15°C. The molting of spiders from one instar to the next was not synchronized with other spiders of the same instar in the field. Spiders overwintered twice (6th instar and adult). The spiders matured in the fall in response to shorter day length. The shortage of food in the field probably limited growth. The duration of an instar was decreased 1.65 days per degree between 12 and 30°C and decreased with increasing feeding rate. The rate of development in the field was increased by higher microclimate temperatures and reduced by lower feeding rates. The surface temperatures of the litter were a mean 1–4°C warmer than air temperature with maximum difference of 23°C. The temperature about 1 inch below the surface of the litter was 4°C lower than surface temperature in less shaded areas and 8°C lower in more shaded areas. There was a direct correlation between the amount of litter and spider density. Spider activity was greatest during the coolest part of the daylight hours. The ecological “zero” was about 10°C, since spiders could not molt at this temperature. The population densities of eggs, 7th instar, and male spiders were estimated at 72,000, 4914, and 1170 per 1.5 acre, respectively, and mortality approximated a logarithmic decrease. The sex ratio was 1:1 T. kochi occupied 45% of the 1.5-acre study area, and all stages were distributed throughout the area occupied. The adult males and 7th-instar spiders traveled 12 and 3 ft per day respectively. Females produced a mean 48 mg of eggs and this fact accounted for the increase in weight of the females between November and April and the increase in weight of the females over the males. The individual efficiency (wt gain/ingestion) and ecological efficiency (wt gain/prey captured) were 32.5 and 19.1%, respectively. The young spiders had a smaller capacity for ingestion, required more frequent meals, and had a lower chance of survival than larger spiders. The mortality balanced the increased ingestion with age and seemed to be optimal for a population living on a fixed level of available prey biomass. The population energy budget indicated that the biomass of T. kochi dying equaled only 20% of the biomass of the prey captured by T. kochi . Cannibalism could have been the only mortality factor. Cannibalism would allow a population to adjust its density to available prey and maintain itself during periods of low prey density, and would shunt the biomass of small prey captured by the 1st-year population into the 2nd-year population, where it would contribute to reproduction.

Zentralnervöse Steuerung bei Araneiden

There is a linear correlation between the distancea (Fig. 1) of the two marginal glue-threads of a sector and the lengthb of the outermost one in the orbweb of the spiderAranea diadema. Figure 2 shows the spread for a group of 1283 sectors of 66 nets of young and old spiders. The 183 points of the graph are mean readings for the same number of groups of neighbouring sectors which were measured in the different webs. In Figure 3 (fine dotted line) this material is combined in classes, and the mean value ofa is given for each class. This curve coincides closely with the smooth fine one which is obtained by expressing the magnitude of the sectorial angles by the relationb:c (see Fig. 1). The material of the graph Figure 4 is condensed in theb:c-curve of Figure 3, the two almost straight lines (thick striped line fora/b, smooth line forb/c) were constructed from the averages (see footnote 3, p. 183). They run almost parallel (compare labels for measuring units on abscissae and ordinates!). Together with others, these observations support the hypothesis that the movements of the spider are controlled by proportions which are prefered by the central nervous system.

ON THE BIOLOGY OF TWO LATRODECTUS SPIDERS IN PALESTINE.

Summary— Some biological facts have been given concerning L. tredecim-guttatus and L. pallidus in Palestine. Their distribution and development have been dealt with. Special attention was paid to the structure of the web and the role the egg-sacs play in young spiders. The factors regulating the leaving of the sac were stated. Observations have been made on the process of copulation. The nature of the food has been investigated. The question of the amount of venom of both species was given special emphasis, and along with some subsidiary questions an experiment was made to compare the strength of the venom of both Palestinian spiders. It has been shown that in the years in which observations were made the strength of the venom of Latrodectus tredecim-guttatus was greater than that of L. pallidus.