Arthropoda Jointed Legged Animals

Introduction More than a million artrhopods have been identified to date. More than a million artrhopods have been identified to date. More have yet to be discovered More have yet to be discovered Unbelievable diversity of animals Unbelievable diversity of animals

Subphyla Subphylum Chelicerata – spiders, ticks, mites, scorpions, and horseshoe crabs Subphylum Chelicerata – spiders, ticks, mites, scorpions, and horseshoe crabs Subphylum Mandibulata Subphylum Mandibulata Class Crustacea – crabs, lobster, shrimp Class Crustacea – crabs, lobster, shrimp Class Diplopoda – Millipedes Class Diplopoda – Millipedes Class Chilopoda – Centipedes Class Chilopoda – Centipedes Class Insecta - Insects Class Insecta - Insects

Body Plan: Exoskeleton made of chitin Exoskeleton made of chitin Provides protection Provides protection Waterproof – restricts water loss Waterproof – restricts water loss Head, abdomen, thorax Head, abdomen, thorax Some leathery – insects Some leathery – insects Some hard – ticks, crabs, lobster Some hard – ticks, crabs, lobster

Feeding: Every method of feeding is represented by arthropods Every method of feeding is represented by arthropods Herbivores, carnivores, parasites, filter feeders and detritus feeders Herbivores, carnivores, parasites, filter feeders and detritus feeders Some are specific, some (locusts) eat anything green Some are specific, some (locusts) eat anything green Some crabs and insects eat other live animals Some crabs and insects eat other live animals Some eat animals and plants already dead Some eat animals and plants already dead External parasites, internal parasites External parasites, internal parasites Filter feeders – barnacles Filter feeders – barnacles

Respiration: 3 types of respiration 3 types of respiration 1. gills 1. gills 2. book gills and book lungs 2. book gills and book lungs 3. tracheal tubes 3. tracheal tubes

Respiration: Book gills – Limulus, and book lungs spiders are arranged like pages in a book – more surface area

Internal Transport: Well developed heart Well developed heart open circulatory system – some vessels, but open into tissues open circulatory system – some vessels, but open into tissues Blood moves into sinuses where it collects and is returned to the heart Blood moves into sinuses where it collects and is returned to the heart

Excretion: Solid wastes leave through the anus Solid wastes leave through the anus Nitrogen wastes are removed in various ways Nitrogen wastes are removed in various ways These are bathed in blood inside body sinuses These are bathed in blood inside body sinuses The tubules remove wastes from the blood, concentrate it and then add it to undigested food before it leaves the body The tubules remove wastes from the blood, concentrate it and then add it to undigested food before it leaves the body

Excretion: Aquatic arthropods – diffusion through unarmored places on the body Aquatic arthropods – diffusion through unarmored places on the body Many aquatic arthropods (Lobster for one) use a pair of “green glands” Many aquatic arthropods (Lobster for one) use a pair of “green glands”

Response: Most have well developed nervous systems Most have well developed nervous systems all have a brain that consists of a pair of ganglia in the head all have a brain that consists of a pair of ganglia in the head Pair of nerves run around esophagus and connect brain to spinal cord that runs around ventral side of body Pair of nerves run around esophagus and connect brain to spinal cord that runs around ventral side of body Several more ganglia, one for each body segment usually, coordinate movement of wings and legs. (That is why they can still flap wings, or walk around after the head is cut off) Several more ganglia, one for each body segment usually, coordinate movement of wings and legs. (That is why they can still flap wings, or walk around after the head is cut off)

Response: Compound eyes w/ as many as 2000 separate lenses Compound eyes w/ as many as 2000 separate lenses Can detect color and motion very well – ever try to swat a fly? Can detect color and motion very well – ever try to swat a fly? Human eye vs. Insect eye  Blades of a fan, UV light Human eye vs. Insect eye  Blades of a fan, UV light

Response: Sense and taste receptors (may be in strange places such as legs, or antennae) Sense and taste receptors (may be in strange places such as legs, or antennae) Sensory hairs feel the movement of air or water Sensory hairs feel the movement of air or water May have well developed ears – eardrum in grasshopper is behind the legs - can hear sounds humans can’t May have well developed ears – eardrum in grasshopper is behind the legs - can hear sounds humans can’t

Protection: Exoskeleton Exoskeleton Can drop a claw or leg to get away Can drop a claw or leg to get away Camouflage Camouflage

Movement: well developed muscle systems well developed muscle systems generate force by contracting and transfer force to exoskeleton generate force by contracting and transfer force to exoskeleton

Reproduction: Males and females produce sperm and egg Males and females produce sperm and egg Fertilization occurs within the body of the female Fertilization occurs within the body of the female

Growth and Development: Molting Molting Epidermis digests inner part of exoskeleton and absorbs much of the chitin Epidermis digests inner part of exoskeleton and absorbs much of the chitin Secretes a new exoskeleton under the old one Secretes a new exoskeleton under the old one

Growth and Development: Arthropod comes completely out of its old exoskeleton Arthropod comes completely out of its old exoskeleton Commonly eats old exoskeleton, then grows then hardens – what is the first thing to harden in a lobster molt? – mouthparts so it can eat the old exoskeleton (recycle the chitin) Commonly eats old exoskeleton, then grows then hardens – what is the first thing to harden in a lobster molt? – mouthparts so it can eat the old exoskeleton (recycle the chitin)

Carcinus maenus

Cancer irroratus

Callinectes sapidus

Uca minax

Libinia emarginata

Subphylum Chelicerata spiders, ticks, mites, scorpions, and horseshoe crabs

Characteristics: 2 part body 2 part body mouthparts called chelicerae mouthparts called chelicerae lack sensory “feelers” found on other arthropods lack sensory “feelers” found on other arthropods

Horseshoe Crabs: Limulus polyphemus Limulus polyphemus Not true crabs Not true crabs Over 430 million years old Over 430 million years old Living fossils Living fossils 5 pr walking legs 5 pr walking legs spikelike tails spikelike tails up to 60 cm long up to 60 cm long

Horseshoe Crabs: