nematoda + int to arthropods

Which major clade includes the Ecdysozoa, Lophotrochozoa, and Deuterostomia?

Bilateria

What is the key defining feature shared by all Ecdysozoans?

A cuticle or exoskeleton

What evolutionary process do Ecdysozoans undergo to grow?

Exoskeleton molting (ecdysis)

What trait is shared by the common ancestor of Ecdysozoans and Deuterostomes?

Bilateral symmetry

How many tissue layers do animals in the Bilateria clade possess?

Three tissue layers

Which sister group to Ecdysozoa does not belong to the Deuterostomia?

Lophotrochozoa

Are most animals classified within the Bilateria clade?

Yes

What type of data unifies the 8 phyla of Ecdysozoans?

Molecular data

Name two phyla of Ecdysozoans that have paired appendages.

Onychophorans and Arthropods

Which phylum within Ecdysozoa has jointed appendages?

Arthropoda

How many species are estimated to be in the Phylum Nematoda?

About 25,000 species

How many species are estimated to be in the Phylum Arthropoda?

About 1,000,000 (1 million) species

What is the estimated number of species in Phylum Loricifera?

10 species

What is the estimated number of species in Phylum Priapula?

16 species

What is the estimated number of species in Phylum Tardigrada?

800 species

What is the estimated number of species in Phylum Onychophora?

110 species

What is a common name for an organism in Phylum Onychophora?

An onychophoran

What is a common name for an organism in Phylum Priapula?

A priapulan

What is a common name for an organism in Phylum Tardigrada?

Tardigrades (water bears)

What is the common name for organisms in Phylum Nematoda?

Roundworms or pinworms

Give an example of an arachnid shown in the slides.

A spider

What type of microscopy is used to show the detailed surface of the tardigrade?

Colorized SEM (Scanning Electron Microscopy)

What type of microscopy is used to show the loriciferan?

LM (Light Microscopy)

How many layers does the Ecdysozoan cuticle typically have?

Three-layered cuticle

What are two physical benefits of the Ecdysozoan cuticle?

It is tough but flexible, and it helps with water loss

What is the definition of ecdysis?

The shedding of the cuticle/exoskeleton as the animal grows

Where are nematodes a dominant component of the animal community?

In the soil community

What proportion of all land animals do nematodes account for?

An estimated four-fifths (80%)

Do nematodes occupy multiple trophic levels in the soil food web?

Yes, they have all major trophic levels

Where do many free-living nematode species reside?

In soils and compost

What ecological role do bacteria-eating nematodes play?

Bacteria-vores involved in nutrient cycling

What major organ system do nematodes completely lack?

A circulatory system

What is the size range of nematodes?

From microscopic to 3 feet long

What type of body cavity do nematodes have?

A pseudocoelom (false coelom)

What structure forms the barrier between a nematode and its environment?

The cuticle

The nematode cuticle is what type of matrix?

An extracellular matrix

What is the predominant protein component of the nematode cuticle?

Small, extensively crosslinked collagen-like proteins

What non-collagen protein layer is found in the nematode cuticle structure?

Cuticlin

Name the outermost coat layer of the nematode cuticle.

Surface coat

What are the regular structural rings or grooves on a nematode's surface called?

Annulus and annular furrow

Name the three primary structural zones of the nematode cuticle beneath the epicuticle.

Cortical, Medial, and Basal zones

What tissue layer lies directly beneath the nematode cuticle?

Hypodermis

Which global survey mapped soil nematode abundance and functional groups?

van den Hoogen et al. (2019) published in Nature

Which terrestrial biome shows a massive total abundance of soil nematodes?

Tundra / Boreal forests

Name five functional trophic groups of soil nematodes.

Bacterivores, Fungivores, Herbivores, Omnivores, and Predators

What is the name of the famous nematode model system?

Caenorhabditis elegans

What biological fields heavily utilize C. elegans as a model system?

Developmental biology, cell biology, and neurobiology

What major milestone did C. elegans achieve in 2002?

Its genome was fully sequenced

Why was the C. elegans genome project historically significant?

It was the first complete sequenced genome of a multi-cellular eukaryote

What is the name of the comprehensive data resource for C. elegans biology?

WormBase (www.wormbase.org)

What is the approximate physical length of an adult C. elegans?

1 mm

Name three parasitic forms of nematodes highlighted in the lecture.

Human hookworm, Heartworm in dogs, and Root knot nematodes

Which type of nematode interacts destructively with plant roots?

Root knot nematodes

What is the scientific name for the soil-transmitted helminth known as the human hookworm?

Ascaris lumbricoides

In what harsh chemical solution can Ascaris lumbricoides eggs survive?

Formalin

What clinical conditions can heavy hookworm infections cause in humans?

Malnutrition and bowel obstruction

Which larval stage of the hookworm penetrates human skin?

L3 larvae

What is the skin irritation caused by penetrating hookworm larvae called?

Ground itch

Through which organs do hookworm larvae migrate before being swallowed?

The lungs and alveolar spaces

Where do adult hookworms mature, feed, and reside inside humans?

The small intestine

How are hookworm eggs shed back into the environment?

Passed in feces

What is the scientific name for heartworm in dogs and cats?

Dirofilaria immitis

How is heartworm transmitted from one host to another?

Through a mosquito bite

Where do juvenile heartworms migrate to complete final maturation?

The heart and pulmonary arteries

What are the young offspring of heartworms found in the blood called?

Microfilaria

How long can adult heartworms live inside the right heart of a dog?

Up to 7 years

Which parasitic nematode causes the disease Trichinosis?

Trichinella spiralis

Where do Trichinella spiralis larvae typically encyst themselves?

In muscle tissue

Which genus of nematodes is transmitted via contaminated fish and squid?

Anisakis

What is the infective larval stage of Anisakis found in fish?

L3 larva

How do humans accidentally become infected with Anisakis?

By consuming raw or inadequately processed contaminated fish or squid

What animal group serves as the definitive host where Anisakis matures into an adult?

Marine mammals

Which non-nematode phylum shares a prominent parasitic lifestyle with nematodes?

Platyhelminthes (Flatworms)

How many times do nematodes typically shed their cuticle via ecdysis?

Usually 3-4 times in a life cycle

Which phylum is described by zoologists as dominating the Eumetazoans?

Phylum Arthropoda

What three domains of nature do arthropods successfully occupy?

Land, sea, and air

How many species of arthropods have been discovered?

Over 1.2 million species

What is the estimated individual abundance of arthropods on Earth?

10^18 (1 billion billion) individuals

What are the three major lineages of modern Arthropods?

Chelicerata, Myriapoda, and Pancrustaceans

Which two groups are united under the lineage Pancrustaceans?

Crustaceans and Hexapoda (insects)

Give an example of an organism in the lineage Chelicerata.

Spiders (or scorpions/arachnids)

Give an example of an organism in the lineage Myriapoda.

Centipedes (or millipedes)

What three key characteristics make arthropods so evolutionary successful?

A rigid exoskeleton, segmentation, and jointed appendages

Which cell layer produces the arthropod chitinous exoskeleton?

The epidermis

What carbohydrate polymer makes up the rigid structure of the arthropod exoskeleton?

Chitin

Chemically, what type of biological molecule is chitin?

A polysaccharide

What materials are complexed with protein to form the multilayered exoskeleton?

Calcium and chitin

What are two major internal functions of the rigid arthropod exoskeleton?

Provides protection and a surface for muscle attachment

Arthropod segmentation and a hardened exoskeleton allowed the evolution of what?

New locomotion and gas exchange mechanisms

What is a primary evolutionary theme regarding arthropod body regions?

Specialization of body regions (regionalization)

Name the freshwater crustacean used to demonstrate jointed appendages.

The red swamp crayfish

What are the primary sensory appendages located on an arthropod's head?

Antennae

What are the three main body regions (tagmata) of a crayfish or insect?

Head, thorax, and post-genital region (abdomen/tail)

What structural feature allows an arthropod's rigid legs to bend?

Jointed appendages moved by attached internal muscles

Contrast the muscle arrangement of an endoskeleton versus an exoskeleton.

Endoskeleton muscles attach externally to bone; exoskeleton muscles attach internally to the shell

What crucial terrestrial benefit does the chitinous exoskeleton provide?

Waterproofing (reduces evaporative water loss on land)

Why did the aquatic exoskeleton predispose arthropods to invade land?

It provided physical stability for walking on dry land without collapsing

What physiological system controls the process of molting (ecdysis)?

Hormonal and neuronal control

Which specific organ produces the ecdysteroid hormone responsible for molting?

The Y-organ

How is the old cuticle prepared for shedding during ecdysis?

It is partially digested by enzymes