Are Spined Micrathena Spiders Poisonous? Debunking Myths & Facts

Spined Micrathena spiders are a type of orb-weaver known for their distinctive appearance, often featuring black bodies with white markings and five pairs of black spines on their abdomens.

While their unique appearance may inspire curiosity and perhaps even fear, the question of whether they are poisonous or not is quite relevant.

In the world of spiders, it is essential to differentiate between “poisonous” and “venomous.”

 

 

Although the Spined Micrathena spider bites can be painful, they do not pose any significant danger to humans.

These spiders use their venom for capturing and immobilizing their prey but are not considered a threat to people due to the low potency of their venom.

Emphasizing the fact that Spined Micrathenas are not harmful, there are no reports suggesting serious consequences following the bite of a spined micrathena spider.

To sum it up, Spined Micrathena spiders, despite their intimidating appearance, are not considered poisonous to humans.

They use their venom to subdue and digest their prey but pose minimal risk to people who encounter them.

No severe reactions have been reported, and interactions with these spiders can be fascinating rather than dangerous.

Spined Micrathena Overview

Identification

The spined micrathena is a distinctively shaped orb-weaver spider.

Females typically have a dark-spotted, whitish or yellowish abdomen, surrounded by five pairs of black-tipped spines.

Males, on the other hand, are much smaller and do not have the characteristic spines.

The spined micrathena’s colors can vary from whitish to yellowish, mottled with black or brown. The spiny abdomen sets them apart from other spider species.

 

 

Scientific Classification

The spined micrathena belongs to the:

• Phylum: Chelicerata
• Class: Arachnida
• Order: Araneae
• Family: Araneidae
• Genus: Micrathena

Some other species in the Micrathena genus include:

• M. gracilis
• M. mitrata
• M. sagittata

Habitat and Distribution

Spined micrathena spiders and other spiny orb-weavers can be found across North and Central America.

Their habitat includes the neotropical regions, extending from the southern United States to as far south as Argentina.

They are commonly found in the forests near lagoons and ponds.

Physical Characteristics

Size and Shape

• Female spined micrathena spiders have a distinct abdomen shape with 5 pairs of black cones.
• Males are much smaller and seldom seen.

The spined micrathena is known for its unique appearance, differing in size and shape between females and males.

Size

• Females: Measuring significantly larger
• Males: Smaller in size, often not noticed

Coloration

• Spined micrathena colors can vary from whitish to yellowish.
• Patterns include mottled black or brown.

The coloration of the spined micrathena often includes white or yellow baselines and features black or brown patterns, adding to their distinct appearance.

 

 

Examples of colors

• Whitish
• Yellowish

Spines and Other Features

• Females have 10 spines on their abdomen.
• Underside of abdomen is cone-shaped.
• Legs are glossy black.

The most striking features of the spined micrathena are the spines and other structures on their bodies.

Females exhibit a spiky abdomen, while the underside is cone-shaped and displays a unique pattern. In addition to these features, both males and females have glossy black legs.

Web and Prey

Web Structure and Silk

Spined Micrathena spiders create circular webs in their natural habitat, often found in hardwood forests and around hickory trees.

These webs are designed to capture small insects such as flies. Key characteristics of their webs include:

• Centered on a tree branch or foliage
• Made of strong, silk-like material
• Circular shape with a spiral pattern

The silk produced by the Spined Micrathena is very strong, which ensures the stability and durability of the web.

Prey Selection and Hunting

The primary prey for the Spined Micrathena are small insects, which they hunt by patiently waiting in the center of their webs.

They are particularly skilled at capturing insects like:

• Flies
• Wasps
• Beetles

These spiders choose their prey based on size and proximity to their web.

Once the prey is caught in the web, the Spined Micrathena quickly immobilizes it and wraps it in silk for later consumption.

Here’s a comparison table of these spiders’ prey selection:

Insect	Common in Spined Micrathena’s diet?
Flies	Yes
Wasps	Yes
Beetles	Yes
Ants	No
Mosquitoes	No

Spined Micrathena are active hunters and are capable of quickly responding to the slightest vibration in their web, allowing them to efficiently catch and consume their prey.

 

 

Behavior and Life Cycle

Mating and Reproduction

The Spined Micrathena spider is known for its distinctive appearance, particularly in females, which are black with white markings and have five pairs of black cones/spines around their abdomen.

Males are smaller and rarely seen in their habitat.

These spiders typically inhabit the eastern United States, including Missouri, where they can be found around vegetation near ponds and lagoons.

During mating, male Spined Micrathena spiders court the females by vibrating their webs.

After mating, female spiders create an egg sac, which contains the developing eggs.

The well-protected sac is often hidden in nearby vegetation to prevent predation by birds and other animals.

Growth and Development

Spined Micrathena spiderlings emerge after their eggs have hatched.

They begin their life as tiny spiders, adapting to their habitat and developing their distinctive features as they grow.

A Spined Micrathena spider’s life cycle includes several stages, such as egg-laying, hatching, and maturation of the spiderlings.

These spiders construct orb-shaped webs, often featuring a tightly coiled spiral design.

These webs are used for capturing prey, and the spiderlings will develop their web-building skills as they grow.

They have a relatively short lifespan, typically surviving for only one season.

• Spined Micrathena Males:

  • Smaller size
  • Less distinctive appearance compared to females
  • Rarely seen
• Spined Micrathena Females:
  • Larger size
  • Distinctive appearance with spines
  • More common in sightings

Spined Micrathena spiders are not known to be harmful to humans, so encountering one while exploring their habitat or going on a hike shouldn’t pose any threat.

 

 

Are Spined Micrathena Spiders Poisonous? Venom and Danger to Humans

Bite and Venom

The Spined Micrathena spider is not known to have a venomous bite that poses danger to humans.

Their venom is geared towards subduing their prey, mainly insects, rather than causing harm to humans. For example:

• The Spined Micrathena’s venom is effective on insects.
• Their bite is not considered dangerous to humans.

Risk to Humans

In most cases, Spined Micrathena spiders are considered harmless to humans.

While it is possible to be bitten by one, the potential harm is minimal, and there is a low risk of serious health complications. Some general points to consider:

• Spined Micrathena bites are often painless or mildly irritating.
• These spiders are not aggressive, and bites usually occur when accidentally disturbed or pressed against the skin.

Here’s a comparison table to clarify the Spined Micrathena’s risk to humans compared to other venomous spiders:

Spider	Venomous	Risk to Humans
Spined Micrathena	Yes	Low
Black Widow	Yes	High
Brown Recluse	Yes	High

In summary, while the Spined Micrathena spider possesses venom, they are not dangerous to humans.

The bites, while potentially uncomfortable, are not a significant cause for concern.

 

 

Ecological Significance

Role in Ecosystem

The spined micrathena is a spiny orb-weaver spider found in Missouri. Its colors vary from whitish to yellowish and are mottled with black or brown.

These spiders are essential for controlling insect populations within their ecosystem. Some examples of insects they consume include:

• Flies
• Mosquitoes
• Moths

While the spined micrathena may appear intimidating due to its unique appearance, such as the ten-spined, chunky abdomen and amber carapace, they pose no threat to humans and are not poisonous.

Threats and Predators

Spined micrathena spiders, like many other orb-weaver spiders, face various challenges and predators. Some common predators include:

• Birds
• Praying mantises
• Larger spiders

Their black blotches and arrow-shaped body serve as a form of camouflage, helping them blend into their surroundings and avoid predation.

Here’s a comparison table showcasing some similarities and differences between spined micrathenas and the closely related arrowshaped micrathena spiders:

Feature	Spined Micrathena	Arrowshaped Micrathena
Abdomen Spines	10 spines	Fewer spines
Color	Whitish to yellowish	Similar
Blotches	Black or brown	Similar
Size (Female)	Larger	Smaller
Web Type	Orb-shaped	Similar
Poisonous to Humans	No	Similar

These spiders’ behavior and unique appearance contribute to their ecological significance in controlling insect populations and displaying the intricate balance of predator-prey relationships within their environment.

 

 

References

The spined micrathena (Micrathena gracilis) is a type of orbweaver spider known for its distinct appearance.

Female spiders are usually black with white markings and have five pairs of black cones/spines on their abdomen.

While their appearance can be intimidating, these spiders are not considered dangerous to humans.

Regarding their venom:

• Spined micrathena spiders have venom
• Their venom is primarily used to paralyze their prey²

Comparison of spined micrathena and more dangerous spiders:

Feature	Spined Micrathena	Dangerous Spiders (e.g., black widow)
Appearance	5 pairs of spines	No spines on the abdomen
Venom Potency	Mild; not harmful	Potent; could be harmful to humans

Features of spined micrathena:

• Orb weaving spider
• Unique body shape with spines
• Not harmful to humans

Pros and Cons of spined micrathena:

Pros:

• Harmless to humans
• Beneficial for controlling insect populations³

Cons:

• Can be intimidating due to unique appearance

In summary, while spined micrathena spiders have venom, it is not harmful to humans.

Their presence in the environment is beneficial for controlling insect populations.

Footnotes

1. Penn State Extension – Spined Micrathena ↩

2. University of Arkansas – Spined Micrathena ↩

3. Missouri Department of Conservation – Spined Micrathena ↩

Conclusion

Spined micrathena spiders are orb-weaving spiders that have distinctive spines on their abdomens.

They are not poisonous to humans, but they can bite if provoked or threatened. They are venomous, however.

Spined micrathena spiders are common in wooded areas, where they build their webs between trees and shrubs.

They feed on flying insects that get caught in their sticky silk. Spined micrathena spiders are harmless and beneficial arachnids that add beauty and diversity to the natural world.