Body Anatomy:
Chelicerates (Chelicerata) are a group of arthropods that includes harvestmen, scorpions, mites, spiders, horseshoe crabs, sea spiders, and ticks. There area about 77,000 species of chelicerates alive today. Chelicerates have two body segments (tagmenta) and six pairs of appendages. Four pairs of appendages are used for walking and two (the chelicerae and the pedipalps) are used as mouth parts. Chelicerates have no mandibles and no antennae. |
Habitat: There isn't a set habitat because this subphylum is predominantly terrestrial although some marine species also exist.
Diet: Early chelicerates were predatory arthropods but modern chelicerates have diversified to take advantage of a variety of feeding strategies. Members of this group are herbivores, detritivores, predators, parasites and scavengers. Most chelicerates suck liquid food from their prey. Many chelicerates (such as scorpions and spiders) are unable to eat solid food due to their narrow gut. Instead, they must expel digestive enzymes onto their prey. The prey liquifies and they can then ingest the food. Reproduction: Horseshoe crabs, which are aquatic, use external fertilization, in other words the sperm and ova meet outside the parents' bodies. Their trilobite-like larvae look rather like miniature adults as they have full sets of appendages and eyes, but initially they have only two pairs of book-gills and gain three more pairs as they molt. Being air-breathing animals, the living arachnids use internal fertilization, which is direct in some species, in other words the males' genitalia make contact with the females'. However in most species fertilization is indirect. Male spiders use their pedipalps as syringes to "inject" sperm into the females' reproductive openings, but most arachnids produce spermatophores (packages of sperm) which the females take into their bodies. Courtship rituals are common, especially in the most powerful predators, where males risk being eaten before mating. Most arachnids lay eggs, but all scorpions and a few mites keep the eggs inside their bodies until they hatch and offspring rather like miniature adults emerge. |
Life Cycle of a Spider:
Interesting Facts about Spiders:
2. Spiders with hair on them are considered mammals which allow them to produce milk. 3. A single strand of spider web has more potential energy than the bomb dropped on Nagasaki. 4. A spider egg has more DNA than four humans combined. 5. In China their exist a collection of 'Holy' spiders hatched over 2,800 years ago. 6. The Kenyan Applecrosser spider grows almost flawless Emeralds on their abdomens. 7. The Snow Spider's body is completely white and it spins a completely black web. |
After mating with a male, the female spider produces an egg sac that can contain up to a thousand tiny spider eggs. The egg sac is made of silk, and the color varies from species to species. In some species, the female spider carries the egg sac on her spinnerets or in her jaws until the eggs hatch. In other species, the egg sac is hidden under a rock, attached to a plant stalk, or encased in a web. Tiny spiderlings (baby spiders) hatch from the eggs - they look like tiny versions of an adult spider. Some spiderlings are on their own and receive no care from their mother. Other spiders climb onto their mother's back after hatching, where she feeds them. In some species, the mother dies when the young are ready to go off on their own, and the spiderlings eat her carcass.
Interesting Facts about Ticks:
1. There are over 850 species of ticks, most of which are capable of transmitting diseases.
2. Ticks feed on the blood of their hosts. 3. Females are larger than males, and the adult size is no bigger than an apple seed. 4. Ticks can detect their hosts by body odor, temperature, moisture and vibrations. 5. Ticks can survive without food for 200 days. |