26 biology

26.1 Many arthropods have an Exoskeleton made up of chitin. What are the advantages / disadvantages to an exoskeleton?

- Advantage: tough and durable - Disadvantage: heavy; the largest known living insect is 11 inches. Beyond that, they have to live in the water where they are weightless. - Disadvantage: obstacle to body growth; must molt exoskeleton to grow.

26.4 Class Insecta God uses His creation to accomplish His purposes. The book of Exodus tells how God dealt with Pharaoh of Egypt to force him to release the captive Israelites. Of the 10 plagues God sent upon Egypt, which three involved insects? (Plagues of Locusts) (How locusts perceive the signal to swarm)

1. Lice were miraculously made from the dust and sent to annoy the Egyptians 2. Swarms of flies were sent 3. Locusts (probably a type of grasshopper) were sent and ate every plant in Egypt

26.4 Class Insecta A few insect species do not exhibit metamorphosis; the majority do. What is metamorphosis?

A change in shape or form that an animal undergoes in its development from egg to adult.

26.1 Worms are tissue invertebrates, phylum Annelida. They have a Closed circulatory System; their blood is contained within blood vessels. Describe the circulatory system of an arthropod.

Arthropods have an Open circulatory system - blood is not limited to blood vessels; with a dorsal heart. Oxygen diffuses directly into body tissue from blood into animals with an open circulatory system.

26.3 Chelicerata (ca-lis-er-a-ta) Although some arachnids do have painful stings and a few transmit diseases, most are completely harmless to man. Only two in the US are dangerous: Which two?

Black Widow & Brown Recluse (Brown Recluse)

26.4 Class Insecta What defense mechanism does the beetle possess? (Bombardier Beetle)

Bombardier Beetle sprays acid out of its rear when threatened

26.3 Chelicerata How do Spiders undergo respiration?

Book Lungs: Air enters spider through slits in abdomen. It flows between page-like folds in the book lungs, where oxygen and carbon dioxide are exchanged. Book Lungs, tracheal tubes, and mantle cavities are all types of respiratory structures in terrestrial invertebrates.

26.4 Class Insecta Biological Rhythms are those mechanisms that cause organisms to regularly change their location. Explain Circadian rhythm vs. Seasonal Cycle

Circadian rhythm - happens daily Seasonal Cycle - Example: Migration Lunar Rhythms - associated with phases of the moon. Example: Lunar based reproductive cycle of the Malaysian Forest Rat

26.2 Crustacea Crustaceans reproduce by way of external sexual reproduction. Crabs and Crayfish

Crayfish- Male transfers sperm to the body of the female using his swimmerets. She stores the sperm until she lays her eggs in the spring, when they are fertilized as the pass out of the oviduct. In five to six weeks, young are hatches and released. Crabs go out to sea at the same time; gametes are released at high tide and find female.

26.4 Class Insecta How do insects obtain nutrition?

Digestive system is virtually the same for all insects. Liquid wastes are converted from ammonia to uric acid in the kidneys. Excretion removes metabolic wastes from the body.

26.4 Class Insecta The process of metamorphosis takes one of two major routes: Incomplete metamorphosis and complete metamorphosis Describe Complete Metamorphosis (controlled by hormones; 90% of all insects - flies, mosquitoes, moths) (Amazing Life Cycle of a Monarch Butterfly)

Egg Larval (segmented worm-like stage; example is maggot, grubs, wigglers, and caterpillars. Main goal in this stage is to EAT; does not resemble an adult of the same species) Pupal (form a cocoon; dismantle and reshape organs) Adult stages (Example - Butterfly) (Video - Bot Fly Maggots)

26.4 Class Insecta The process of metamorphosis takes one of two major routes: Incomplete metamorphosis and complete metamorphosis Describe Incomplete Metamorphosis.

Incomplete Metamorphosis Examples: grasshopper, cicadas, true bugs 3 stages are: Egg, Nymphal (miniature, oddly-proportioned adult; resembles an adult of the same species) & Adult stages

26.4 Class Insecta How are insects different than other arthropods like Chelicerata (spiders) and Crustacea (Crayfish)?

Insects have three pair of walking legs; a body divided into a head, thorax and abdomen; one pair of sensory antennae; and usually wings. Most insects fly.

26.1 There are many more invertebrates than vertebrates. The largest animal phylum is Arthropoda ("Jointed Feet"). 4 out of 5 animal species are arthropods, with new ones being discovered daily. Name some examples of Arthropods.

Insects, scorpions, crabs, lobsters, & spiders. Can you visualize the jointed feet?

26.4 Class Insecta Insect defense behaviors are both innate and learned. Insect behavior is a good testimony to God's careful design and care, even for some of his smallest creatures.

Moths have eye-like markings on their hind wings. When disturbed, the moth will lift its front wings to expose these markings that look like eyes. The predator sees it and leaves the moth alone.

26.3 Chelicerata (ca-lis-er-a-ta) How do spiders obtain nutrition? Did you know that spiders can attack and eat fish and small birds?

Spider immobilizes prey..... Then it injects digestive juices into it. Muscular pharynx sucks out partially digested matter and moves it to stomach.

26.4 Class Insecta What is so special about the way Termites digest?

Termites have cellulose-digesting microorganisms in their digestive tract, which help the termite consume the wood. It is a symbiotic relationship because both species benefit.

26.3 Chelicerata (ca-lis-er-a-ta) A Subphylum of arthropods is Chelicerata - arachnids, horseshoe crabs, and seas spiders What are some characteristics that make arachnids distinct from other arthropods?

The body is divided into a cephalothorax & an abdomen. They have four pair of walking legs. They usually have four pair of simple eyes. They do not have antennas or mandibles.

26.2 Crustacea A Subphylum of arthropods is Crustacea - lobsters, crabs, crayfish, shrimp, snowbugs, barnacles. What are some characteristics of Crustaceans?

The body is divided into two segments: the cephalothorax and the abdomen. They possess two pair of antennae and perform respiration by the use of gills.

26.4 Class Insecta How does an insect breath? Book Lungs, tracheal tubes, and mantle cavities are all types of respiratory structures in terrestrial invertebrates.

There are small pores along each side of the insect. The insect breathes as its abdominal contractions pump air into and out of the tracheal system. Alveoli and book lungs increase the surface area of respiratory membranes.

26.2 Crustacea May of these Crustacea molt. The exoskeleton is nonliving and cannot grow, so the arthropod (crayfish in this case) must periodically molt in order to get bigger. Molting is the process by which an arthropod sheds its skeleton and manufactures a larger one. Explain further. (video)

To molt, the arthropod produces enzymes that eat away at the inside of the old exoskeleton while a new skeleton is produced beneath it. Some arthropods then take in water and air to swell and rupture the old shell; others may wiggle out.

26.4 Class Insecta Can insects see, touch smell, hear, taste?

Touch - Tactile hairs on the antennae, limbs, and body provide for the sense of touch Hearing - some possess a tympanum & some listen with an organ located in each foreleg Smell - usually centered in the antennae Taste - receptors are abundant in mouth parts. Butterflies have chemical receptors for taste on their legs.

26.1 Arthropods have Jointed appendages & Body Segmentation. Explain.

Typical arthropod has a head, thorax, and abdomen.

26.4 Class Insecta Both Exoskeleton and endoskeleton animals have joints. Joints provide flexibility and freedom of movement. How do the legs move? (Centipede vs. grasshopper mouse)

When the flexor muscle is contracted, the leg bends. When the extensor muscle contracts, the leg straightens. Using human leg in picture, but same applies to animal anatomy, though humans are unique and distinct from animals in that we are made in the likeness and image of God.

26.4 Class Insecta Can insects see, touch smell, hear, taste?

Yes! Insects have compound eyes give visual range; they detect color and form images. Simple eyes respond to light only. (Mosaic vision) (How insects see the world)

26.1 Do arthropods have a nervous system?

Yes; Ventral nervous system - brain connected to an anterior ganglion and a ventral nerve cord Remember - Dorsal is to the back; ventral is to the belly.

26.3 Chelicerata (ca-lis-er-a-ta) Arachnids have four pair of appendages: 1) One pair of chelicerae 2) One pair of pedipalps 3 & 4) Two pair of walking legs Describe the chelicerae (ca-lis-er-I) & the pedipalps

chelicerae (mouthparts) - have poisonous fangs to paralyze prey pedipalps are for sensory reception & in males for sperm transfer