Animal biodiversity

Question 1

What are the main cells of porifera?

Answer 1

Pinacocytes, choanocites, amoebocytes and oocytes. There is also scleroblast and they are in charge of making the spicules

Question 2

Where does the gamete formation take place in porifera?

Answer 2

Oogonia for the oocytes (female gametes) and directly from the flagelar cells in the case of male cells

Question 3

Describe the epidermis of a sponge

Answer 3

Epidermis is fomed by pinacocytes and choanocytes (monociliated and the cilium is surrounded by a ring) the choanocytes move the cilia to create a stream of water throught the canal system.

Question 4

How do sponges trap their food?

Answer 4

The collars in the choanocytes trap the particles and then this particles are endocytazed, ameobocytes transport the material (cell trasnport)

Question 5

Name the autapomorhies of porifera

Answer 5

Choanocytes
Basal calcareous skeleton

Question 6

What are the evolutionary novelties that appear with porifera and are maintained in other metazoans?

Answer 6

Clone of cells
Gap junctions
Extracellular matrix with collagen
Septate junctions
Apical adhaerens junctions
Epithelia
Diploid chromosomes
Oogenesis 1 egg + 3 polar bodies
Free sperm cells
Radial cleavage, blastula

Question 7

Characteristics of metazoan epithelia

Answer 7

Has a polar structure
Basal side bears receptors and firmly adheres to proteins on the basal lamina
Basal lamina is composed mostly of type IV collagen, lamin and fibronectin
Ephitelium cells are linked by: occluding junctions (osmotic barriers), gap junctions (signal exchange) and cell junctions
It ALWAYS separates an internal from an external side

Question 8

If an animal had a gut but no vascular system to distribute nutrients within the body, where would you expect to find the gonads? Nemerteans possess a blood vascular system. Does your answer to this question also applies for Nemerteans. If not, please explain in which way the gonads are supplied with nutrients.

Answer 8

Next to branching gut
Yes they are located between neighbouring midgut caecae

Question 9

Nemerteans are the longest worms that life in the marine system. What was the evolutionary success of being long? Why was body length positively selected?

Answer 9

They have gonads on each segment, which is supplied with nutrients by gut pouches. So more bodylength=more gonads and better survival for offspring

Question 10

Entoprocts perform rapid rocking movement that are restricted to a very few seconds. During the movements the calyx is bend back and forward. Which muscles are responsible for this?

Answer 10

Longitudinal muscles in the stalk

Question 11

Filter feeding in entoprocts can be performed due to specific ciliary movements.

Answer 11

Currents from lateral cilia on tentacles -> compound lat cilia push org mat to frontal cilia band -> org mat transported to ciliary band on food groove on atrial ridge and then to the mouth

Question 12

Summarize the synapomorphies of mollusks and entoprocts

Answer 12

Dorsal protein chitin cuticle, mouth and anus on same side, blood lacunal system, larvae has gliding sole, flat ventral surface with cilia, dorso-ventral muscles

Question 13

What is the benefit from having a larva? Why evolved larvae?

Answer 13

Juvenile and adult habitats are different so less competition and also dispersal
More specialized morphology for just eating, if the adults are more specialized in rep. they are more successful

Question 14

Why are metanephridial systems, like the one in Mollusca, always correlated to secondary body cavities, whereas protonephridia can be found in any mesoderm organization, i.e. acoelomate, pseudocoelomate and coelomate?

Answer 14

Because you need a blood vascular system, if you want to have cells that ultrafilter you need a blood vessel that provides something to filtrate, the filtration system needs to be connected to the vessel to have a direction and have a space to put the final product

Question 15

Some mollusks are very large animals. What evolutionary novelty (autapomorphy) in their stem lineage was a prerequisite to attain larger body sizes?

Answer 15

Lacunal system+pumping system=heart

Question 16

Torsion and later asymmetrical arrangement of certain organs are gastropod characters that represent import and successful evolutionary innovations. Please find out (a) how (not what for) torsion evolved, (b) which organs were affected by asymmetries

Answer 16

A : modification of embryonic development (but what the fuck ‘how did it evolve’ even mean)
B : ass heart kidney more frontal, gills frontal
1gill, 1 kidney, 1gonad, 1 gonoduct

Question 17

The crystal cone was an important evolutionary innovation, most likely already in the stem lineage of the Conchifera. Please check the literature and other sources to infer its function.

Answer 17

Crystalline Style : matrix of protein+amylase, Sorts stomach content by releasing enzymes while rotating+grinding against gastric shield.small enough particles are caught in sorting ridges and are transported to midgut

Question 18

Please explain the role of the midgut gland (mid gut diverticulum, digestive gland, midgut pouch) in Mollusca.

Answer 18

It only holds the smallest particles the animal can endocytose, basically a one way system of absortion

Question 19

Nautilus species are horizontally oriented in the water. For what functional reasons must their shell be coiled?

Answer 19

It places the center of gravity closer to the geometrical center so that way they can swim horizontally in a more stable manner, the chambers to regulate the flotation also are arranged in the shell so as the shell grows the chambers grow and the relation is maintained, in straight shell cephalopods the “tip” of the shell has to have a more rapid growth to add material and maintain the cephalopod horizontally, also the coil gives an advantage in locomotion as turning is easier

Question 20

Why is the straight shell of cephalopods always an internal shell? What would happen, if they had a straight external shell? Are such representative known in the recent or past fauna? Please check out by using different resources

Answer 20

If they had a straight shell they couldnt inject air further enough in the end of their shells
So prehistoric straight shelled molluscs stayed with tentacles facing substrate
ex)Orthocerida

Question 21

The aesthetes of polyplacophorans are used to perceive information from the surrounding environment. Some of them are lensed eyes. They are interconnected and distributed across the shell plates. Please explain their function

Answer 21

Changes in light intensity, movement, some simple images, shadows

Question 22

Bivalves have to open shell plates for feeding. Please describe which structures are involved in closing and opening the shell of bivalves. Please explain in which way this organization and feeding mode limits the distribution of bivalves

Answer 22

Adductor muscles(closing shell), ligament and resilium(keeps shell open)
Must remain in aquatic environment for filterfeeding, on land they will dry out + base state is open shell
Filtration impossible+locomotion is hard af on terr. Habitats, needs sand

Question 23

Mytilus edulis and Ostreas edulis inhabit the lower and intertidal zone. What limits their distribution towards the sublitoral and towards the upper intertidal?

Answer 23

Upper zones are blasted by the sun longer=drying out+starvation:
Lower filtration rate, and thus the time to recover the energy to close the shell it would arrive to late

Question 24

Summarize all those structures that are segmental in Annelida.

Answer 24

Dorsal and ventral cheatal sacs, coelomic cavities separated by mesentery, metanephridia, nervous system (ganglia), circular muscles, gonads, blood vessels