Homework's 1-7

Invertebrates make up over 96% of the described animal species.

True

Diploblasts lack which germ layer?

mesoderm

All protostomes are triploblasts.

True

If a single cell is removed from a protostome embryo, both the embryo and the cell will continue to develop into larvae.

False

In spiral cleavage, cells lie directly on top of one another.

False

Diploblasts are acoelomates.

False

An example of a pseudocoelomate is a

Round worms

Animals adapted for directed forward movement most likely have

bilateral symmetry

An organism is considered to have organ grade complexity when similar cells aggregate into patterns or layers.

False

A hydrostatic skeleton is important to coelomates but not acoelomates or pseudocoelomates.

False

List in order,from most inclusive to least inclusive, the classic Linnaean ranks for animals.

Domain, Kingdom, Phylum, Class, Order, Family, Genus, And Species

_________________ is the preference for the lease complex explanation

Parsimony

_________ is the science of group organisms together based on their evolutionary history.

Systematics

A taxon is polyphyletic if it excludes the most recent common ancestor of all members of the group.

True

A taxon is paraphyletic if it includes the most recent common ancestor of all members of the group and some, but not all, of its descendents.

True

An example of a homology is the character of

hair in mammals

A homoplasy is a character trait that is shared due to common ancestry.

False

List 3 features sponges are know to lack.

1. No True Tissues

2. Symmetry

3. Nervous System

Explain how water flows through the leuconoid canal system. Include the all body structures where the water enters, where it goes next, and where it exits the sponge. What cells direct this water flow? (Note: you must use your own words. Copy and paste from lecture notes or the internet will result in a zero for this question. You will need to be able to answer this type of question on an exam so now is the time to practice writing an answer when you have access to your notes.)

Water flows through the leuconid canal system by entering the Ostia through the incurrent canal, passing through the flagellated chambers, where it gets filtered, moves into the excurrent canals, and finally exits the sponge through the osculum. The choanocytes are the key cells that direct and maintain the flow.

Which cell type secretes fibers made of collagen?

Collenocyte

Which cell type secretes fibers made of a protein called spongin?

Spongin

Cnidarians are eucoelomates.

False

An operculum is a lid covering the capsule containing the coiled thread of a cnidocyte.

True

Nematocysts are produced by cnidocytes.

True

Nematocysts are a type of cnidae.

True

The light sensing structures in scyphozoan jellyfishes that are located in the rhophalia are

Ocelli

Write an essay using full sentences, describing the life cycle of Aurelia. Include all the life stages, asexual and sexual reproduction. (Note: you must use your own words. Copy and paste from lecture notes or the internet will result in a zero for this question. You will need to be able to answer this type of question on an exam so now is the time to practice writing an answer when you have access to your notes.)

The Aurelia has both asexual and sexual reproduction. During sexual reproduction, the male medusa sheds its sex cells from the gonads into the gastrovascular cavity, which are then discharged through the mouth. When discharged, the female medusa takes in the sex cells to fertilize her eggs and start the internal fertilization process. This process forms a zygote. Once the zygote is mature, it forms a free-swimming planula larva. This larva will then attach to a substratum and develop into a sessile polyp called Scyphistoma. The polyp then goes through a process called strobilation to produce a strobila, which makes multiple ephyrae. When the ephyrae mature, they form a mature medusae. The medusae then detach from the substratum, and the process starts again. When it comes to asexual reproduction, it is the same process as sexual it just happens within one medusae.

zygote brooded by female strobilization is the asexual reproduction in the polyp, not the medusa stage

Humans get infected with Schistosoma trematodes by

swimming in the water with cercariae

The definitive host of Taenia pisiformis becomes infected by eating

rabbit infected with a cysticercus.

Platyhelminthes are acoelomate, with mesoderm.

True

Organisms belonging to subphylum Lophotrochozoa are

diverse with some acoelomates, pseudocoelomates, coelomates

Gastrotrichs are

monoecious

Organisms in phylum Rotifera are

Pseudocoelomates

Acanthocephalans (spiny-headed worms) are odd members of phylum Rotifera.

True

In annelids, the blastopore becomes the anus.

False

Organisms in class Errantia differ from other annelids because they have paired parapodia on most segments.

True

Each internal compartment of an annelid is lined with peritoneum, a layer of mesodermal epithelium.

True

A leech has a clitellum only during the breeding season.

True

Gas exchange in the earthworm occurs through the setae.

False

Describe in detail the Errantia body plan and parapodia structure and how they move. Write in full sentences and in your own words using terminology covered in lecture.

The body plan of organisms in Class Errantia is uniquely designed for active movement and predatory or scavenging lifestyles. These annelids have a segmented body, a distinctive feature, with each segment containing paired, fleshy appendages called parapodia. The parapodia, another distinguishing feature of Errantia, plays a crucial role in locomotion and respiration. Each parapodium is composed of two lobes: a dorsal notopodium and a ventral neuropodium. These lobes are structurally supported by aciculae, chitinous rods that provide the necessary structural support. The parapodia also bear numerous setae, or bristle-like structures, which aid in gripping the substrate and propelling the organism through water or across surfaces. In some species, the parapodia are highly vascularized, allowing them to also function in gas exchange. Errant polychaetes employ a unique mode of locomotion, using a combination of muscular contractions and parapodial movements. They use wave-like contractions of their longitudinal and circular muscles, a movement known as undulatory locomotion. As these muscles contract on one side of the body, the parapodia on that side extend outward and push against the substrate or water, generating forward motion. The alternating contractions on the left and right sides produce a rhythmic, coordinated movement that allows them to crawl, burrow, or swim efficiently. In aquatic species, the parapodia function similarly to oars, pushing against the water to create propulsion. This makes Errantia well-suited for a mobile and often predatory lifestyle, as they actively seek food rather than remain sedentary like their Class Sedentaria counterparts.

prostomium peristomium pygidium

Cultured pearls are made by placing an irritating particle between the mantle and the shell.

True

Polyplacophora lack gills.

False

Most freshwater clams have a bivalve glochidia stage that attaches to the gills and lives as a parasite for a few weeks.

True

The periostracum is the outermost shell layer, made of conchin (protein) and secreted by the mantle fold in molluscs.

True

A major disadvantage of coiling in gastropods is the anus moved over the mouth, which results in fouling problems.

False

The copulatory organ of male cephalopods is the pedipalp, a modified labial palp.

False

In molluscs, coelom formation occurs from mesoderm cells that form near the blastopore and then migrate.

True

The nitrogenous waste in mollusks is removed by flame cells.

False

When dissecting a mollusk such as a clam, you would find the coelom around the heart area only.

True

Cephalapods have a muscular sole-like foot.

False