Arthropods Organisms with jointed appendages, a segmented body and a tough exoskeleton

Key Terms Exoskeleton – a tough external covering Chitin – a carbohydrate that is a component of the exoskeleton Appendage – structures that extend from the body like legs and antennae Trachael tube – a network of branching tubes that extend throughout the body through which the arthropod respires

Key Terms Spiracle – openings located along the side of the body Book lung – organs that have layers of respiratory tissue stacked like the pages of the book (generally found in spiders) Malphighian tubule – saclike organs that extract wastes from the blood Molting – the shedding of the exoskeleton of an arthropod

Sub-phyla of Arthropods Crustaceans – typically have two pairs of antennae, two or three body segments, and chewing mouthparts called mandibles (include crayfish, lobsters, and crabs) Chelicerates – have mouthparts called chelicerae and two body sections, and nearly all have four pairs of walking legs (include spiders, ticks, horseshoe crabs) Insects – body is divided into three parts – head, abdomen and thorax, three pairs of legs are attached to the thorax. (includes grasshoppers, etc)

Crustaceans Crustaceans – Two pairs of antennae, two or three body segments, and chewing mouthparts called mandibles (EX.crayfish, lobsters, and crabs) Body plan has two segments (Cephalothorax and abdomen). Carapace covers the cephalothorax Appendages vary in location and function Mandibles – mouthpart adapted for chewing or grinding of food.

Crustaceans Chelipeds – first pair of legs that bear large claws modified to catch, pick up, crush, and cut food. Swimmerets – flipperlike appendages used for swimming located along the abdomen Respires through gills on the underside of the body

Sub-phylum Crustaceans

Chelicerates Have two pairs of appendages attached near the mouth adapted as mouthparts Chelicerae – first pair that contains fangs that are used to stab and paralyze prey. Pedipalps – longer than the chelicerae and usually modified to grab prey This class includes horseshoe crabs and spiders, mites, ticks and scorpions

Arachnids Include horseshoe crabs, spiders, mites and ticks, and scorpions Spiders do not have jaws to chew their prey, but inject venom which paralyzes their prey and then liquifies the preys insides so it can suck the tissues into their stomach Spiders have spinnerets for silk

Arachnids Mites and ticks are often parasitic. The mouthparts or chelicerae and pedipalps are designed for digging into their host’s tissues. Ticks can transmit some serious diseases such as Lyme Disease or Rocky Mountain Spotted Fever.

Arachnids Scorpions usually are found in warm areas Their pedipalps are enlarged to form claws The abdomen has a stinger that carries venom that can kill or paralyze prey. These critters will chew their prey using their chelicerae.

Arachnid - anatomy

Dangerous Spiders in the US Black Widow Black shinky body with red/orange hourglass shape on abdomen Venom – neurotoxic (affect nervous system) Bites can be fatal (general in small children or elderly individuals)

Dangerous Spiders in the US Brown Recluse Violin shape on cephalothorax Venom – hemolytic (affect blood cells thus killing tissues)... death of tissues surrounding bite Bites are fatal to small children and older individuals

Dangerous Spiders in the US Brown Recluse Violin shape on cephalothorax Venom – hemolytic (affect blood cells thus killing tissues)... death of tissues surrounding bite Bites are fatal to small children and older individuals

FYI: Black Widow Bite Renders no pain… at the beginning Then it feels like damage by a small pin. As the below picture shows, two tiny red spots can be generally seen at the center point of the swollen area. But soon the venom spreads and the injury grows in size, reddeness, and dead tissue. It is very necessary that the victim attends to an emergency room in day number one; also, succeeding in trapping the spider to show it to the doctor could be helpful at the time of prescribing the exact medication.

Insects Also known as Uniramians and have one pair of antenna, jaws and unbranched appendages. Centipedes (Chilopoda) – have many legs, the number depends on the species Are carnivores and have venomous claws to catch, stun or kill their prey Must live in the moist area since their spiracles will not close and their exoskeleton is not waterproof.

Insects Millipedes (Diplopoda) – highly segmented body and each segment has 2 pair of legs Timid creatures and feed off of dead or decaying material Live under rocks and in logs. Roll into a ball to protect the soft undersides when disturbed.

Insects Insects (Insecta) – have body divided into three segments (head, thorax and abdomen) and three pairs of legs attached to the thorax. Typical insect will also have a pair of antenna, a pair of compound eyes on the head, two pairs of wings on the thorax and tracheal tubes for respiration.

Insects - Responses Many sense organs – eyes, antennae with chemical receptors for taste and smell and also in the mouthparts and legs Sensory hairs that detect movements in their surroundings. Ears are also well developed and are found behind the legs in the grasshopper.

Insects – Feeding Various types of mouthparts – and saliva that performs many functions Chewing – used mandibles Sucking – moth uses a proboscis Spongelike – used a spongelike mouthpart to lap up food Piercing – for penetrating the object upon which to feed

Insects – Feeding and Mouthparts

Insects - Metamorphosis Growth and development includes metamorphosis where the body and shape of the organism changes Complete metamorphosis 4 basic stages (egg, larva, pupa, and adult) Incomplete metamorphosis 3 basic stages (egg, nymph, and adult)

Insects Interactions with Humans Many negative impacts for humans – Can you name a few?

Insects Interactions with Humans How about listing some of the benefits from insects?

Insect Communication Visual cues – such as fireflies lights to communicate with females. Chemical signals – aka pheromones - which are specific chemical messengers that affect the behavior or development of other individuals of the same species. When could humans use pheromones within their interactions with insects?

Insect Societies Ants, bees, termites and some of their relatives form complex associations called societies. Specialized individuals within societies form castes where the individual has a special body form for its role (ex. Queen bee in the hive, worker bees, etc)

Insect Communication in Societies A system of communication is necessary for functioning within a society. Ex. Ants find food and leave a trail for others to follow and retrieve food Bees have two basic dances for communication – waggle dance and round dance