a spider known as a cross spider usaually found in the uk
Arachnic
a garden spider
The distinctive feature of a red spider with a yellow back is its unique coloration, which sets it apart from other spiders.
The spider you are describing is the Golden Silk Orb Weaver spider (Nephila clavipes). It is known for its large size, distinctive shape like a shield, golden yellow color, and unique back spikes. It is also recognized by its brown and yellow striped legs.
The spider you are referring to is likely the yellow sac spider. Yellow sac spiders are brown with two yellow stripes on their back and are commonly found in California. They are not considered aggressive towards humans but can deliver a painful bite if provoked.
Based on your description, it sounds like you might have a species of jumping spider, possibly a bold jumper (Phidippus audax). These spiders are common in North America and are known for their black coloration with distinctive markings like yellow dots and colorful chelicerae (fangs). Jumping spiders are active hunters and are not considered dangerous to humans.
your mummy spider
Every spider in Australia has some venom, However it is not deadly.
It is called the black widow spider (Referred to as the black widow), it is a spider with a strong neurotoxin. With respect to the body size, they have longer legs and smaller abdomen. They are usually dark brown, has yellow stripes, and a yellow hourglass spot.
Your spider is a Heartstring spider the prettiest spider ever.
Argiope aurantia Lucas - yellow garden spider