Invert Test 5

What type of development do arthropods have?

Protostomes

What type of body cavity do arthropods have?

Eucoelomate

What type of symmetry do arthropods have?

Bilateral symmetry

Why are arthropods the most successful group of animals?

Extremely adaptable and can live in nearly every environment (oceans, deserts, forests)

What is tagmatization (tagmosis)?

Fusion of somites/metameres into functional body regions

What are the main body regions formed by tagmosis?

Cephalothorax (head + thorax) and abdomen

What is metameric segmentation?

Division of the body into a linear series of repeating similar segments (same repeating segment)

What are the four main reasons for arthropod success?

-Exoskeleton (muscles attach here)

-Jointed appendages (speed)

-evolution of flight

-efficient organ systems

What does the hypodermis secrete for arthropods?

cuticle of chitin

What is the exoskeleton made of?

Lipoprotein + chitin

What additional component is found in crustacean exoskeletons?

CaCO3

What are key properties of the exoskeleton?

Waxy, water impermeable, no gas exchange

What secretes the cuticle (exoskeleton)?

Epidermis

What is sclerotization?

Hardening of the cuticle with protein (starts soft)

What varies in the exoskeleton?

Thickness (joints stay soft and flexible)

What are the main functions of the exoskeleton? (hint 4)

-Support and protection

-prevents desiccation

-movement

-specialized functions

How does the exoskeleton protect the organism?

Protects organs, defends against predators, helps capture prey, protects from chemical changes

How does the exoskeleton prevent desiccation?

Acts as a watertight barrier

How does the exoskeleton aid movement?

Provides a rigid skeletal system

What specialized functions can the exoskeleton have?

Sensory structures, mouthparts, defense, wings, copulatory organs

What is ecdysis?

molting

Why must arthropods molt?

The exoskeleton cannot grow.

What happens after molting?

The organism is soft and very vulnerable to predators.

What is the function of jointed appendages?

Rapid and efficient locomotion

Why are jointed appendages efficient?

Provide leverage and allow antagonistic muscle pairs

What type of muscles do arthropods have?

Striated (skeletal) muscles

Why are striated muscles important?

Faster contraction → enables movement and flight (flight is the superstar here)

What is the super important reason for striated muscles?

allowed insects to achieve flight

How do arthropod muscles compare to other invertebrates?

Others mostly have smooth muscle (slower)

What is the advantage of flight in arthropods?

Habitat dispersal and access to more niches

What does flight allow arthropods to do?

Inhabit more diverse ecosystems

How is the arthropod nervous system organized?

Similar to annelids but with greater cephalization

What are the main components of the nervous system?

Cerebral ganglia, double ventral nerve cord, segmental nerves (lateral pair nerves)

What do neurosecretory cells do?

Act as both nervous and endocrine cells

What do neurosecretory cells control?

Reproduction, metamorphosis, osmoregulation, eye pigments, color change (just know like 2)

What type of circulatory system do arthropods have?

Open circulatory system

What does the open circulatory system do?

Movement of nutrients, salts, hormones, respiratory gases and metabolic wastes throughout the body

What fluid circulates in arthropods?

Hemolymph

What does the heart do in arthropods?

Pumps hemolymph

What is the flow of hemolymph?

Heart → open arteries → hemocoel (body cavity)→ body movement pushes hemolymph → ostia (opening to the heart)→ back to heart

What are ostia?

Openings that allow hemolymph to re-enter the heart

What is hemolymph made of?

10% hemocytes and 90% plasma

What is the most common (important) respiratory pigment in arthropods?

Hemocyanin

What metal is in hemocyanin?

Copper

What color does hemocyanin turn when oxygenated?

Bright blue

Where is hemocyanin found?

Dissolved in blood plasma

What is hemoglobin in arthropods?

Iron-based pigment (less common)

How is oxygen actually delivered in many arthropods?

Tracheal system (NOT circulatory system)

What determines the type of respiratory system in arthropods?

Their habitat (aquatic vs terrestrial)

Which respiratory systems are used in aquatic arthropods?

Cutaneous respiration and gills

What is cutaneous respiration for aquatic species?

Gas exchange directly through the body surface

Which arthropods use cutaneous respiration in aquatic species?

Small arthropods (microscopic crustaceans, some small spiders in moist habitats)

What are gills used for in aquatic arthropods?

Gas exchange in aquatic environments

Why are gills efficient for gas exchange?

Large surface area exposes blood-rich tissue to oxygen in water

How are gills ventilated?

Movement of appendages

What are 'book gills' in aquatic species?

Modified gills found in horseshoe crabs

Which respiratory systems are used in terrestrial arthropods?

Book lungs and tracheal system

What are book lungs in terrestrial species?

Folded membranes that increase surface area for gas exchange with air.

Which terrestrial arthropods use book lungs?

Spiders and scorpions.

What is the function of the tracheal system?

Delivers oxygen directly to cells in tubes

What is the pathway of air in the tracheal system?

Spiracle → tracheal tubes → tracheoles → cells

What are spiracles?

External openings for air intake

What are tracheal tubes lined with?

Taenidia (support rings)

What are tracheoles?

Small branches that deliver oxygen directly to cells

Why is the tracheal system highly efficient?

Direct oxygen delivery → rapid ATP production

Which organisms use the tracheal system?

Insects, millipedes, centipedes, some arachnids

What nitrogenous waste do aquatic arthropods excrete?

Ammonia

Why is ammonia toxic?

Requires dilution with water

How is ammonia eliminated?

Through permeable membranes (ex: gills)

What nitrogenous waste do terrestrial arthropods excrete?

Uric acid

Why is uric acid beneficial?

Can be excreted as a dry material → conserves water

What are nephridia?

Structures that extract waste and produce urine

Which arthropods have nephridia?

Most aquatic arthropods and some terrestrial ones

What are green glands also called?

Maxillary glands or antennal glands

What do green glands do?

Excrete waste (especially ammonia)

Which organisms have green glands?

Crustaceans

What are coxal glands?

Excretory structures found in arachnids and horseshoe crabs

What do coxal glands do?

Excrete waste

Which arthropods use Malpighian tubules?

Terrestrial arthropods (especially insects)

What is the function of Malpighian tubules?

Remove nitrogenous waste and regulate water balance

How do Malpighian tubules work?

Salts and uric acid move from hemolymph into tubules → water follows by osmosis

What happens in the hindgut for Malpighian tubules?

Water and salts are reabsorbed

How are wastes excreted with Malpighian tubules?

With feces through the anus

What is the advantage of Malpighian tubules?

Conserves water by excreting waste as a dry paste (most efficient)

What is the phylum?

Arthropoda

What is the taxonomy for trilobita? Everything

Kingdom- Animalia, subkingdom- Eumetazoa, phylum- arthropoda, subphylum- trilobitomorpha, class- trilobita

What is the origin for the name trilobites?

the 3 pleural lobes, 1 central and 2 lateral

What is the status of trilobites?

Extinct arthropods from the Paleozoic Era

How long ago did trilobites go extinct?

About 300 million years ago

Why are trilobites considered highly diverse?

10 orders, 150 families, 5000 genera, >17,000 species

Where have trilobite fossils been found?

On all continents

What typical arthropod traits did trilobites have?

Exoskeleton, metameric segmentation, jointed appendages

What are the three main body regions of trilobites?

Cephalon (head), segmented thorax, pygidium (tail)

Why are trilobites called 'trilobites'?

They have three pleural lobes (1 central, 2 lateral)

What trophic roles did trilobites have?

Detritivores, predators, scavengers

What is the taxonomy for chelicerata?

phylum- arthropoda, subphylum- chelicerata

class- merostomata, pycnogonida, arachnida

What are the 3 classes in subphylum chelicerata?

Merostomata (Horseshoe crab), Pycnogonida (sea spiders), Arachnida (arachnids)

What does being subphylum chelicerata entail?

you have chelicera

What are the two body regions in chelicerates?

Cephalothorax (prosoma) and abdomen (opisthosoma)

What are chelicerae?

One pair of appendages used for catching food and defense