BJU Organismal Biology (Zoology) Unit 3 Test: Ch. 19-21

Phylum Arthropoda

Contains over three-fourths of all known species

Their abundance and wide ecological distribution make them the most diverse animal group

1,100,000

How many species of arthropods have been recorded?

true

T/F Some arthropods are serious disease agents and compete with humans for food; others are beneficial

true

T/F Arthropods are ecdysozoan protostomes belonging to clade Panarthropoda

Segmented bodies

Chitinous cuticle

Jointed appendages

What are the three key physical characteristics of Arthropods?

Myriapoda

Centipedes, millipedes, pauropods, and symphylans are placed in subphylum...?

Hexapoda

Insects are placed in subphylum...?

Chelicerata

Spiders, ticks, horseshoe crabs and their relatives form subphylum...?

Crustacea

Lobsters, crabs, barnacles, and others form subphylum...?

- Versatile exoskeleton

- segmentation and appendages provide for more efficient locomotion

- air piped directly to cells

- highly developed sensory organs

- complex behavior patterns

- use of diverse resources through metamorphosis

Why have arthropods achieved such great diversity and abundance?

cuticle

Highly protective but is jointed, providing mobility.

- an inner thick procuticle

- an outer thin epicuticle

What are the two layers of cuticle within Arthropods?

sclerotization

What is the protein within the cuticle layers strengthened by?

chemical cross-linking

What is sclerotization?

Exocuticle secreted before a molt

Endocuticle secreted after molting

What layers are excreted by the procuticle?

chitin

Both layers of procuticle contain __________ bound with protein

Ecdysis (molting)

The process of shedding an outer covering and growing a new, larger one

a linear series of similar somites (blocks of mesoderm) with jointed appendages

What is the primitive pattern of segmentation and appendages within arthropoda?

tagmata

Many somites may be fused or combined into specialized groups called?

Through an efficient tracheal system that delivers oxygen directly to cells

How is oxygen delivered to cells in terrestrial arthropods?

They respire via various forms of efficient gills

How is oxygen delivered to cells in aquatic arthropods?

vary from simple light sensitive ocelli to compound mosaic eyes

How are eyes in arthropods ranged?

touch, smell, hearing, balancing and chemical reception

What other senses do Arthropoda organism include?

true

T/F Arthropods surpass most other invertebrates in complex and organized activities

true

T/F Most complex behavior patterns are innate or unlearned, while only some Arthropod species have learned behaviors

different larval and adult stages

Many arthropods have metamorphic changes that result in?

true

T/F Larvae and adults of Arthropods eat different foods and occupy different habitats and avoid competition

Subphylum Chelicerata

Characteristics of...?

- Bodies composed of two tagmata: a cephalothorax and abdomen

- Have six pairs of cephalothoracic appendages

- lack mandibles and antennae

Cephalothorax (prosoma)

Abdomen (opisthosoma)

What are the two tagmata of subphylum chelicerata called?

chelicerae

pedipalps

four pairs of legs

What do the six pairs of cephalothoracic appendages within subphylum chelicerata include?

Horseshoe crabs

Class Merostomata: Subclass Xiphosurida includes?

true

T/F The modern horseshoe crab is nearly unchanged from ancestors in the Triassic period

- an carapace (unsegmented shield) covers the body in front of a broad abdomen and a telson (tailpiece)

- the cephalothorax has four pairs of walking legs, a pair of pedipalps, and a pair of chelicerae

- Abdomen bears six pairs of broad, thin, appendages fused in the median line

- Book gills exposed on some of the abdominal appendages

What structures are included within Class Merostomata

Chelicerata

Class Merostomata belongs to the subphylum?

Chelicerata

Class Arachnida belongs to the subphylum?

true

T/F Most Arachnids are free living and more common in warm, dry regions

- two tagmata: cephalothorax and abdomen (sometimes segmented)

- cephalothorax bearing chelicerae, pairs of pedipalps, and four pairs of walking legs

- lacks antennae and mandibles

- most are predaceous and have claws (modified pedipalps), fangs (modified chelicerae), venom glands, or stingers

- sucking mouthparts ingest the fluids and soft tissues from bodies of their prey

- Spiders have spinning glands

What structures make up class Arachnida?

over 80,000 species

How many species of Arachnida have been described?

true

T/F Most Arachnids are harmless to humans and provide essential control of injurious insects

- some spiders are venomous and can cause pain or death in humans

- ticks may carry human diseases

- mites can be crop pests

How are some members of Arachnida pests to humans?

Spiders

What organisms belong to order Araneae?

40,000

How many species of spiders are known?

characteristics of spiders

- body consists of an unsegmented cepahlothorax (prosoma) and abdomen (opisthosoma) joined by a slender pedicel

- anterior appendages are a pair of chelicerae with terminal fangs

- pair of pedipalps have sensory functions and are used by males to transfer sperm

- all are predaceous, mostly on insects

- injected venom liquefies and digests the tissues which is sucked into the spider's stomach

- breathe by book lungs and/or tracheae

- Species of black widow spiders are dangerous; the venom is neurotoxic

- the brown recluse spider has hemolytic venom that destroys tissue around the bite

Are spiders really dangerous?

Scorpions

Order Scorpionida includes what organisms?

characteristics of order Scorpionida

- More common in tropical and subtropical zones but do occur in temperate areas

- About 1,400 species

- stinger on the last segment has venom that varies from mildly painful to dangerous

harvestmen (daddy longlegs)

Order Opiliones includes what organisms?

characteristics of order Opiliones (harvestmen)

- about 5,000 species

- their abdomen and cephalothorax join broadly without a narrow pedicel

- can lose one or more of their eight legs without ill effect

- chelicerae are pincerlike and they feed more as scavengers than do spiders

- not venomous, though they can deter some predators with noxious secretions

Ticks and Mites

Order Acari includes what organisms?

acari

Medically and economically the most important arachnids

characteristics of order Acari (ticks and mites)

- about 40,000 species described, many more estimated

- both aquatic and terrestrial; inhabit deserts, polar areas and hot springs

- most mites are less than 1 mm and ticks range up to 3 cm

- Have complete fusion of cephalothorax and abdomen with no signs of external segmentation

spider mites

One of many important agricultural pest mites that suck out plant nutrients

chiggers

larval Trombicula mites; they feed on dermal tissues and cause skin irritation

ticks

are significant disease vectors, second only to mosquitoes

Lyme disease

Tick species of Ixodes carry what disease?

Rocky Mountain spotted fever, tularemia, and others

Tick species of Dermacentor carry what diseases?

subphylum Myriapoda

What subphylum includes these characteristics?

- include Chilopoda (centipedes), Diplopoda (millipedes), Pauropoda (pauropods), and symphyla (symphylans)

characteristics of class Chilopoda (centipedes)

- found under logs, bark and stones

- carnivorous, eating earthworms, cockroaches, and other insects that they kill with their venom claws.

- terrestrial and have flattened bodies with up to 177 segments

- each segment except one behind the head and the last two, bears a pair of jointed legs

- appendages of the first body segment form venom claws, and the last pair of legs serve a sensory function

- head has one pair of antennae, pair of mandibles, and one or two pairs of maxillae

- eyes on either side of the head consist of groups of ocelli

characteristics of Class Diplopoda (millipedes)

- less active than centipedes; walk with a graceful rather than wriggling motion

- most eat decayed plants but a few eat living plant tissue

- most are slow moving and roll into a coil for defense

- some secrete toxic or repellant fluids

- cylindrical bodies have from 25 to more than 100 segments

- short thorax consists of four segments, each bearing one pair of legs; each abdominal segment has two pairs of legs

- the head has two clusters of simple eyes and a pair of antennae, mandibles and maxillae

repugnatorial glands

Glands within class diplopoda which secrete toxic or repellant fluids on the sides of body

Subphylum Hexapoda

Characteristics of which subphylum within Phylum Arthropoda?

- named for the presence of six legs; all legs are uniramous.

- have three tagmata (head, thorax, and abdomen).​

- two classes: Entognatha and Insecta

Entognatha

Characteristics of what class?

- Small group in which bases of mouthparts are enclosed within the head capsule

- three orders: Protura, Diplura, and Collembola

Protura and Diplura

members of these orders are tiny, eyeless, and inhabit soils or dark, damp places

Collembola

Members of this order are commonly called springtails because of their ability to leap

Insecta

Characteristics of which class?

- members have ectognathous mouthparts; the bases of mouthparts lie outside the head capsule.​

- winged members are pterygotes and wingless members are apterygotes

- most diverse and abundant of all arthropods.​

- Currently 1.1 million species have been classified worldwide, but may be as many as 30 million

- Insects are found in nearly all habitats except the sea.

entomology

The study of insects

- flight and small size facilitate dispersal

- well-protected eggs withstand rigorous conditions and are readily dispersed

- many structural and behavioral adaptations facilitate access to every possible niche

What adaptive traits of insects allow their wide distribution?

wings, antennae, mouthparts and alimentary canal

What are most structural modifications of insects called?

Specialization for eating only one part of a plant

How can many insect species coexist on a plant?

a hard, protective exoskeleton that retains water as well as metabolic adaptations that conserve water.​

How is survival in dry or desert regions possible in insects?

sclerites

The exoskeleton of insects is made of complex plates, or ___________, connected by hinge joints.

muscles attaching to sclerites

How are precise movements accomplished in insects?

The rigidity is due to scleroproteins and not mineral matter; this lightness allows flight.

How is the rigidity accomplished in insect exoskeletons?

true

T/F ​​Tagmatization in insects is homogenous in contrast to the variability found among crustaceans. ​

a dorsal notum

a ventral sternum

pair of lateral pleura

A cuticle of each body segment is composed of...?

- usually pair of large compound eyes

- one pair of antennae; they vary greatly in form but can feel, taste, and hear

- mouthparts consist of a labrum, pair of mandibles and maxillae, a labium, and a hypopharynx

What do the heads of insects include?

- consists of prothorax, mesothorax and metathorax; each has a pair of legs

- wings are cuticular, double-membraned extensions formed by the epidermis, veins serve to strengthen: if two pairs, they are on the mesothorax and metathorax

- walking legs end in terminal pads and claws

What does the thorax of insects include?

true

T/F The vein pattern on the wings is used to identify insect taxa

- the insect abdomen has from nine to 11 segments; the last is reduced to a pair of cerci

What does the abdomens of insects include?

walking and flight

How is locomotion accomplished in insects?

two pairs

one pair

Most flying insects have how many pairs of wings, while Diptera (true flies) have how many pairs?

Halteres

Are reduced wings that provide the fly with balance during flight

- direct flight muscles attach to a wing directly

- indirect flight muscles alter the shape of the thorax causing wing movement

How do direct and indirect flight muscles differ from each other?

Wing is hinged at the thoracic tergum and a pleural process that forms a fulcrum; all insects cause the upstroke with indirect muscles that pull the tergum downward

What is the muscle movement in insects that allows flight?

true

T/F Dragonflies and cockroaches contract direct muscles to pull the wing downward

- Foregut consists of the mouth with salivary glands, esophagus, crop and gizzard

- some digestion, but no absorption, occurs in the crop as salivary enzymes mix with food

- gizzard grinds food before it enters the midgut (stomach and gastric ceca), the main site of digestion and absorption

- ceca may increase the digestive and absorptive area

- hindgut (intestine, rectum, and anus) is primarily a site for water absorption

Characteristics of digestion in Hexapoda

- a tubular heart in the pericardial cavity moves hemolymph forward through the dorsal aorta

- heartbeat is peristaltic wave

- accessory pulsatory organs help move the hemolymph into wings and legs

- open circulatory system

Characteristics of circulation in Hexapoda

- tracheal system

- spiracles open to the tracheal trunks; there are two on the thorax and 7-8 on the abdomen

Characteristics of gas exchange in Hexapoda

tracheal system

a network of thin-walled tubes that branch throughout the insect body

Spiracle valves reduce water loss; the spiracle may also serve as a dust filter

How is water loss reduced in Hexapoda?

tracheae

composed of a single layer of cells lined with cuticle that is shed at each molt

- work in conjunction with specialized resorptive cells in the intestinal epithelium.

- Potassium and other solutes and waste materials are secreted into the tubules, which drain the fluid, or "urine," into the intestine.

- Resorptive cells recapture most potassium and water, leaving behind such wastes as uric acid.

- This recycling of water and potassium allows species living in dry environments to conserve body fluids by producing a nearly dry mixture of urine and feces.

How are Malpighian tubules used in conjunction with rectal glands?

fusion of ganglia

stomodeal nervous system that corresponds in function to the autonomic nervous system of vertebrates

neurosecretory cells located in various parts of the brain play role in molting and metamorphosis

What is the nervous system of Hexapoda

true

T/F Most sense organs of insects are microscopic and are located in the body wall

​​Touch, pressure, vibration, etc. are detected by sensilla (seta or hairlike process)

How is mechanoreception accomplished in insects?

​Sensitive setae (hair sensilla) or tympanal organs may detect airborne sounds.​

How is auditory reception accomplished in insects?

- These usually are bundles of sensory cell processes located in sensory pits.​

​​- They may occur on mouthparts, antennae and legs.​

How is chemoreception accomplished in insects?

- Insects have two types of eyes: simple and compound. ​

​​- Simple eyes are found in many adults; most insects have three ocelli on their heads.​

​​- Compound eyes, found in most adults, may contain thousands of ommatidia.​

How is visual reception accomplished in insects?

cells in antennae and legs. ​

How do insects detect temperature?

true

T/F ​​Insects can detect humidity, proprioception, gravity and other physical properties.​