Tarantulas, known for their often large and hairy appearance, begin their lives as remarkably small creatures. The term “baby tarantula” refers to a “spiderling,” the developmental stage immediately following hatching from the egg sac. This article details the distinctive visual characteristics of these tiny arachnids, highlighting what sets them apart from their adult counterparts and other young spiders.
Defining the Baby Tarantula
A baby tarantula is formally known as a spiderling, sometimes called a “sling.” This stage begins after the eggs hatch within a silk egg sac. Inside this protective sac, which can resemble a golf ball made of silk, hundreds of eggs may be laid by the female tarantula. The spiderlings remain within the egg sac, often for several weeks, where they undergo their first molt. They typically emerge from the sac after this initial molt.
Initially, spiderlings often stay together, sometimes in the maternal burrow, before they begin to disperse. This communal phase allows them to utilize the remaining yolk in their abdomens for sustenance. As they grow, many species will eventually disperse to create their own burrows. This early life stage is characterized by rapid growth.
Key Physical Characteristics
Tarantula spiderlings are notably small, with some terrestrial species measuring around 0.25 inches (6 mm) in diagonal leg span (DLS), while arboreal species might be slightly larger, reaching 0.5 to 0.75 inches (13-19 mm) DLS. The tiniest spiderlings can be as small as 0.125 inches DLS, while larger species can start at approximately 1 inch DLS.
Their coloration is generally less vibrant than adult tarantulas, often appearing pale, whitish, yellowish, or light brown, and sometimes even somewhat translucent. Distinct adult patterns and vibrant hues develop gradually with successive molts. For instance, some species like the Caribena versicolor, begin as blue spiderlings before developing reddish-pink hairs as they mature.
Spiderlings possess body proportions that can appear unique, especially immediately after hatching when they might resemble “eggs with legs” before their first true molt. After this initial molt, their bodies become more defined, resembling miniature versions of adults. Their legs may appear relatively long and spindly compared to their small, sometimes plump, abdomen.
The exoskeleton of a spiderling is delicate and soft, especially right after a molt, before it hardens. They have fine, sparse hairs (setae) covering their bodies, which are less dense and prominent than the urticating hairs found on adult New World tarantulas. Their fangs are present but are tiny and less developed than those of mature tarantulas.
Appearance Changes Through Growth
Tarantulas, like all arthropods, possess a rigid outer shell called an exoskeleton, which does not stretch. To grow, a tarantula spiderling must periodically shed this old exoskeleton in a process known as molting. Each molt allows the spiderling to increase in size and develop a new, larger exoskeleton. Young tarantulas molt frequently.
Before a molt, a spiderling’s coloration may become duller, and its abdomen can appear darker or shinier as the new skin forms underneath. After shedding, the new exoskeleton is soft and pale, gradually hardening and darkening over several days to regain its species-specific color. With each progressive molt, the spiderling’s body proportions become more balanced, resembling the adult form more closely. The distinctive adult coloration and patterns gradually emerge as the spiderling matures through multiple molting cycles.
Distinguishing Tarantula Spiderlings from Other Young Spiders
Identifying a tarantula spiderling among other young spiders requires attention to distinct features. Tarantula spiderlings, even at their small size, generally exhibit a more robust body shape compared to the often more delicate appearance of other spiderlings.
Even in their early stages, tarantula spiderlings may have slightly thicker or more substantial legs relative to their body size compared to the slender limbs of many other young spider species. Their hairiness is another distinguishing characteristic; tarantulas are known for their dense covering of setae, and even fine hairs are noticeable on spiderlings, a feature less pronounced in many other spider families. Their fangs are a key anatomical difference, being primitive and pointing downwards, contrasting with the more advanced, sideways-moving fangs found in most other spider groups. These combined physical traits can aid in their identification.