Lampade e lampadine come alleati nella caccia quotidiana, ponti tra vite in dipendenze interconnesse. La natura sembra eleggere relazioni piuttosto che individui, niente si crea da solo. Chiediti quante moltitudini contieni.
Lamps and lightbulbs as allies in daily hunting, bridging lifeways in entangled dependency. Nature seems to elect relationships rather than individuals, nothing makes itself alone. Ask yourself how many multitudes you contain.
Nome scientifico: Amaurobius erberi (Keyserling, 1863)
Global distribution (WSC 2021): Canary Is., Algeria, Europe (not in UK and northern Europe), Turkey, Caucasus
Caratteristiche anatomiche: L’A.erberi è un ragno di taglia media che va dai 5 ai 10 mm, dall’aspetto robusto e tozzo e colorazione generale scura, tendente al marrone grigiastro. Non ha una colorazione dalla fantasia peculiare, infatti ad occhio è praticamente indistinguibile da A.similis e A.fenestralis. Per una corretta identificazione è necessario osservare i caratteri genitali (palpi nei maschi ed epiginio nelle femmine), che in generale nel mondo dei ragni sono specie-specifici.
Comportamento: Tessitore di ragnatele tubolari, che si estendono in orizzontale, e vengono costruite fra le spaccature della roccia o sui muri. Proprio all’interno del tunnel di seta, il ragno attende la sua preda ignara, che urtando i fili che al suo ingresso si sviluppano in verticale, come colonne, allerta il ragno della sua presenza, a cui consegue un attacco immediato.
Naturalists have long been fascinated with the practices
through which plants lure their insect and animal pollinators. The orchids
are one large family of plants that have garnered significant attention for
the techniques they use to secure fertilization. Charles Darwin was among
a handful of nineteenth-century naturalists who invested extraordinary
time and attention documenting encounters among orchids and insects.
After years of intensive study, his 1862 treatise On the Various
Contrivances by Which Orchids Are Fertilised by Insects exclaimed:
“[H]ow numerous and beautiful are the contrivances for the fertilisation
of Orchids.” In his description of the species Orchis mascula, he insisted,
“[I]n no other plant, or indeed in hardly any animal, can adaptations of
one part to another, and of the whole to other organisms widely remote in
the scale of nature, be named more perfect than those presented by this
Orchis” (28). From the vantage point of his theory of natural selection,
orchid and insect bodies were perfectly articulated to one another, serving
both orchid reproduction and insect nourishment. Darwin delighted
in his ability to discern the mechanical functionality and utility of orchid
Differences flowers and took this as a demonstration that even beautiful forms had
utilitarian, adaptive value. In this sense, his orchid book was to be read as
proof of natural selection and adaptation, indeed, as a study of the hardest
case (Browne, Charles; Desmond and Moore).
Researchers investigating plant pollination ecologies today
engage a set of evolutionary theories that have been modified significantly
since Darwin’s elaboration of natural selection in his 1859 Origin
of Species. Plant and insect behaviors are now grounded in deterministic
models that reduce interactions among species to the actions of “selfish
genes” geared to the task of reducing an organism’s energy expenditure
while maximizing its reproductive fitness for long-term species survival
(see Dawkins, for example). Such neo-Darwinian accounts are endemic
to the burgeoning field known as “chemical ecology” (see Dicke and
Takken, for example). Researchers in this field home in on the chemical
determinants that shape ecological relations, including the pheromones
and other signaling chemicals that organisms secrete to attract, repel, and
communicate with one another. If Darwin described the brilliant range of
colors, flexible forms, sensual textures, and sweet nectars that attracted
pollinators to orchid flowers, today chemical ecologists approach plants
with attentions and instruments attuned to the plumes of volatile chemical
attractants that plants synthesize and release into the atmosphere.
Neo-Darwinian logics are particularly pronounced in studies
currently being conducted on Ophrys orchids (see, for example, Vereecken
and Scheistl; and Vereecken et al.). Many of the numerous species that
comprise the Ophrys genus have the remarkable ability to lure pollinators
in spite of the fact that they do not offer the insects a nectar “reward.”
Chemical ecologists have found that Ophrys species can attract their pollinators
selectively by exhaling volatile compounds that mimic the sex
pheromones of their insect pollinators. These volatile plumes can elicit
“typical” sexual behavior in male insects: for example, scientists have
observed excited male bees swarm around flowers, expose their genitalia
before landing, and engage in “precopulatory movements” as they
feverishly try to mate with the flowers (Nilsson 257). In so doing, the bees
“inadvertently” participate in orchid fertilization.