Arrow-shaped Micrathena (Micrathena sagittata)

The Arrow-shaped micrathena spider has a unique arrow-shaped tummy, which is why it’s named that way! This spider is part of the orb-weaver family and lives mainly in the eastern United States and Central America. This post will share cool facts about this interesting spider.

Physical Description and Identification

Adults

• Size:  The males are 0.20 (5 mm) inches long, while the females are a little larger and have a body length of 0.35 inches (9 mm).
• Color:  The females are more brightly colored than the males who are hardly seen. In fact, the male spiders have a black body with white on the edges, whereas the females have red head and legs. They also have a bright yellow abdomen with red and black spots.
• Other Characteristic Features: They have a long, triangular abdomen resembling an arrowhead.  The females have sharp spines protruding from the edges of their abdomen, which also helps them to keep predators at bay. The males, on the other hand, do not have spines.

Eggs

The eggs are small and round, laid on the sides of the web, near a leaf. They remain in the sac for the winter and hatch the following spring.

Spiderlings

After hatching from the eggs, the spiderlings initially have longer abdomens and shorter spines. As the spiders mature, they acquire an adult-like body pattern.

The Web

The male and female species spin spiral webs positioned vertically in an up-down posture. Most of the webs also have a zig-zag decorative structure called stabilimentum, a little above the middle portion. Like most other orb-weavers, they too rebuild the webs regularly.

Are Arrow-shaped Micrathena Spiders Venomous?

Yes, Arrow-shaped Micrathena spiders have venom. They use it mostly to catch their food.

Can Arrow-shaped Micrathena Spiders Bite?

Yes, they can bite, but it’s rare for them to bite humans. If they do, it’s usually not serious and just causes a little discomfort.

Ecological Importance and Behavior of Arrow-shaped Micrathena Spider

Arrow-shaped micrathena spiders are diligent predators in their ecosystems. By consuming a wide range of insects, they help control pest populations, contributing to the ecological balance within their habitats. These spiders demonstrate daily industriousness by rebuilding their webs, ensuring maximum efficiency for capturing prey.

Natural Predators: Birds and larger insects are the main predators of the Arrow-shaped micrathena. The spiders’ spines and vibrant colors may serve as deterrents, but they are not foolproof against all threats.

Prey-Predator Dynamics: Their diet mainly consists of insects that become ensnared in their sticky webs. The stabilimentum in their web may play a role in capturing prey or even deterring predators by making the web more visible and therefore avoided by larger animals that could destroy it.

Relationship with Humans: Arrow-shaped micrathena spiders are typically harmless to humans. Their presence is actually beneficial as they help in reducing the population of insects that could be pests to human activities. Their bites are rare and generally only result in minor irritation. However, due to their distinctive appearance, they are often noticed and appreciated by nature enthusiasts.

Quick Facts

Did You Know

• Out of the six spikes, the two present at both ends of the abdomen give the impression of spearheads.

In conclusion, understanding the Arrow-shaped micrathena’s way of life gives us a glimpse into the complexity and beauty of ecological interactions.