Starfish, fish frog, rat, embryology lab

How many distinct layers of cells do developing sea stars have at the blastula stage?

2 layers

How large is a frog zygote compared to that of a sea star?

A frog zygote is much larger compared to a small sea star zygote.

Why must an eggshell be porous?

Allows the embryo to breathe oxygen and let out carbon dioxide.

Explain starfish reproduction

Asexual reproduction (regeneration) is starfish takes place by fission through autonomy of arms. In fission, the central disk breaks into two pieces and each portion that regenerates the missing parts. Only certain genera of starfish are able to reproduce in these ways. Sexual- fertilization in water when males release sperm and females release eggs into the environment. The fertilized embryos become part of the zooplankton in most species larvae undergo metamorphosis, settle at the bottom and become adults

What cells give their skin color?

Chromatophone, there are 3 types of pigment cells. Melanophores, xanthophones, and inidophones.

The basic stages of embryological development are remarkably similar for a wide range of organisms. How would you explain such consistency?

Common ancestors/ common genes.

What divides the thoracic and abdominal cavities?

Diaphragm

Where does a sea star embryo get its nutrition during prelate all stages of development?

Diffusion and stored lipids

How has the developing frog embryo dissipated it's metabolic wastes?

Diffusion into the surrounding water.

Sea star and frog embryos do not have membranes similar to those of a chick embryo. How do sea star and frog embryosz accomplish the function of these membranes?

Diffusion of surrounding water.

What aquatic adaptions do you see in the frog?

Eyes and nostrils are positioned high on their head, which keeps them out of water when they swim on the surface. They have a sensitive area on their back hat allows them to sense vibrations through water. Webber feet and valves on nares.

Why are the ectoderm and endoderm called "germ" layers?

Germinate means to develop. The ectoderm and endoderm are the layers developed.

How does the starfish respire?

Hey breathe through there dermal bronchi.

Describe the gonads in the rat.

In the rat, the gonads produce sex hormones. In the males the testes contain glandular interstitial tissue in addition to the sperm producing seminiferous tubules. The interstitial cells function in the synthesis of the male sex hormone testosterone. In the female, the ovarian follicles produce estrogen. These follicles, which also contain the eggs, rupture when an agh becomes ripe. The old follicle then develops rapidly into a new structure, the corpus luteum, which also secretes hormones.

Why is the frog considered to be a tetrapods?

It is a 4 limbed vertebrate

Describe the heart of a rat.

It is like the human heart. The rats heart has 4 chambers, the circulatory mechanism is divided into pulmonary and systemic. The heart acts like a pumping organ. Has and right and left ventricle, right and left atrium, and a septum.

How does the pyloric ceca function?

It secretes enzymes that aid in digestion and can also absorb food.

Describe the water vascular system.

It's a hydraulic system used by echinoderms, such as sea stars and sea urchins, for locomotion, food, waste transportation, and respiration. The system is composed of canals connectively numerous tube feet.

More recently evolved organisms have modified the stages of embryological development. Would you expect early or late stages to be modified the most? Why?

Late stages because the slight changes happen later in development.

List the order of the digestive tract organs from the mouth to the anus.

Mouth, esophagus, stomach, intestine, cloaca, anus.

Is all of the albumen of a chicken egg the same consistency?

No

Are all of the organ systems fully developed in a free- swimming larva? Which organ systems are unlikely to be fully developed?

No and reproductive

Chickens lack a larval stage. How do they compensate for this?

Parental core

What functions does the shell have?

Protect contents of egg from bacteria and prevent moisture from leaving the egg to quickly. Helps nourish it as well as enabling it to develop outside of water.

If you pull a probe through the albumen it seems to cling to the probs and to itself. What macromolecules are abundant in the albumen and make it viscous?

Proteins

Compare the lungs of the rat to the lungs of the frog.

Same: trachea, lungs, nostrils, the function of the respiratory system in both these animals is to supply the body with oxygen rich blood. Differences: frogs have moist skin, diffusion occurs. The lungs in a frog are much simpler then those in a rat, this is less efficient but since frogs are able to use diffusion through their skin they do not require such efficiency. In rats breathing causes ribs to expand to a certain degree because mammals have a diaphragm, frogs are unable to expand their ribs because of this lack of a diaphragm. Because frogs are cold blooded they do not require as much oxygen as warm blooded animals like rats. When frogs are in their tadpole state they have gills to allow them to breathe underwater. Frogs pull oxygen through their nostrils into their mouth by lowering the bottom of its mouth from there the oxygen goes through the glottis and into the trachea. Since frogs do not require as much oxygen as rats they have less Aveo li in their lungs.

What are three external sensory structures

Sense of smell (external nares), sight, and lateral line

How much yolk protrudes through the blastopore of a frog gastrula?

Some of them protrudes as yolk plug.

Name two accessory glands of the digestive system.

Spleen and pancreas

What is the relative size of the frog gastrula compared to the blastula and zygote?

Starts as 20-50 smaller cells, then the embryonic cavity forms more smaller cells. Then it becomes a 3 layered system with a cavity (eventually a digestive tract). Overall stays the same size, simple to complex.

How does orientation of the blastocoel within the blastula compare with that of a sea star?

The frog blastocoel is displaced toward the animal pole.

Where is the starfish mouth and what does it feed on?

The mouth is located on the oral side of it's body. They primarily feed on mullusks. Their main source of food are clams, oysters. And mussels. They also eat snails and injured fish when they can find them.

Which fins have protective spines, what are they used for?

The spiny dorsal fin, used to protect itself from predators.

Explain how frogs breathe through their skin

Their skin is made of thin membranous tissue that is permeable to water and contains a large network of blood vessels. The thin membranous skin allows respirator gases to readily diffuse directly down the gradients between the blood vessels and surroundings. When the frog is out of water, mucks glansin the skin keep the frog moist, which helps absorb dissolved oxygen from the air.

How does the size of an embryo during early cleavage compare with that of the zygote? Is the sea star embryo growing during cleavage?

They are about the same size, it is not growing in size.

What is unique about a frogs tongue

They are attached to the front of their mouths rather than at the back. When a frog catches an insect it throws its sticky tongue out of its mouth and wraps it around it's prey. Then the tongue snaps back and it throws its food down its throat.

Where are the kidneys in the rats

They are located toward the back of the abdominal cavity on either side of the spine. Retroperitoneal.

What are the vomerine teeth used for?

They are small projections in the top of a frog's mouth that function in holding and capturing prey.

As cells invaginate nd move about, do they "know" here they are? If not, how is movement controlled? If so, how long do they perceive their position?

They do know where they are. Stem cells have to know where they are and what they're doing.

What type of symmetry does a starfish have?

They start out with bilateralsymmetry during the larval stage. During metamorphosis they lose bilateral symmetry and develop radial symmetry.

What is the major function of the larval stage in the overall life history of an organism?

To gather and store food so the transformation to the adult stage can occur. (To feed)

The blastomeres of a mature blastula eventually develop cilia and the entire blastula can rotate and move. How is movement important to a developing sea star?

To increase surface contact with water and gain oxygen and get rid of waste.

Which are larger, animal pole cells or vegetal pole cells?

Vegetal pole cells

When a fish respire seems why is it called double pumping?

Water pumps through the mouth and the gills are closed. The mouth closed and the gills are pumping water

Has organogenesis begun for 33- and 72-h chick embryos?

Yes

Is the degenerating blastocoel visible in the frog gastrula?

Yes

Are the cells of the two -called stage of a sea star similar in size.

Yes, because it splits in half into two equal cells.

Are both the egg and the zygote of a sea star the same size?

Yes, because the sperm is so small it doesn't change the size of the fertilized egg (zygote).

Is the developing blastocoel visible in late cleavage?

Yes, it develops from a blastula in late cleavage to a blastocoel in early gastulation.

Are any areas of the frog zygote more darkly pigmented than other areas?

Yes, the animal pole- darkly pigmented. Vegetal pole- lighter hemisphere -opposite of each other.

Is the heart beating in 33- and 72-h chick embryos?

Ys