Biology

What percentage of animals belong to the Phylum Arthropoda?◦ 2/3, 67%

List some examples of arthropods:◦ Lobsters, crabs, spiders, and insects

Like annelids, arthropods are segmented animals.

Body segments bear jointed extensions called appendages such as legs and antennae.

What does “arthropod” mean?◦ Jointed foot

Describe the exoskeleton of arthropods. What is the function of each layer of the exoskeleton?◦ Outer layer: repels water and helps prevent

dessication◦ Middle layer: provides the primary protection ◦ Inner layer: provides flexibility at the joints

What is a compound eye?◦ An eye composed of many individual light

detections, each with its own lens What is molting?

◦ The process by which an arthropod sheds its exoskeleton and develops a new one.

Identify the difference between chelicerae and mandibles.◦ Chelicerae-pincerlike mouth parts◦ Mandibles- jawlike mouth parts

What are the five main subphyla of arthropods?◦ Trilobita, Crustacea, Chelicerata, Myriapoda, and

Hexapoda

What characteristics are shared by most or all crustaceans?◦ Have two pairs of antennae and paired

appendages (some branched).◦ Most have mandibles and a nauplius larva.

What is the most important role of copepods in marine ecosystems?◦ Abundant in the plankton and serve as a food

sources What are some examples of terrestrial

crustaceans?◦ Sow bugs and pill bugs

Why do terrestrial crustaceans only live in moist environments?◦ They lack adaptations for conserving water

Crayfish◦ What are the functions of the mandibles and

chelipeds on a crayfish? Mandibles are used for chewing Chelipeds are used for capturing food and defense.

◦ What structural adaptations of crayfish promote effective respiration in water? Walking and branches of maxillae circulate water

over the gills.

◦ Crayfish (continued):◦ Describe the type of circulation found in a

crayfish. Open circulatory system; the heart pumps

hemolymph into several large vessels. Hemolymph then enters the spaces w/in the body where it bathes the tissues. Hemolymph returns to the gills where it exchanges O2 and CO2. Then, the hemolymph returns to the heart.

List the major characteristics of arachnids:◦ Have a cephalothorax and abdomen.◦ Cepalothorax usually has 6 pairs of jointed

appendages: Chelicerae, pedipalps, and 4 pairs of walking legs

Describe the functions of pedipalps:◦ Aid in holding food and chewing◦ In spiders, they transfer sperm from the male to

the female’s seminal receptacle.

Describe three ways in which spiders are adapted to catching prey:◦ Some spiders spin webs to trap prey. ◦ They also have chelicerae modified as fangs that

inject venom. ◦ Spiders can also immobilize their prey by

wrapping them in silk.

Name two ways in which scorpions differ from spiders:◦ Scorpions have large pincerlike pedipalps and a

stinger at the end of their abdomen

How do mites and ticks differ? ◦ Mites are usually less than 1 mm in length, while

ticks are a few millimeters to 3cm in length. Mites can be free living, but ticks can only be parasites.

How do millipedes and centipedes differ?◦ Millipedes are herbivorous, have rounded bodies,

and have two pairs of legs on most segments.◦ Centipedes are carnivorous, have flattened

bodies, and have one pair of legs on most segments.