Living Organisms 2 Flashcards
1
Q
List the kingdom systems.
A
Plantae, Animalia, fungi, Protista, eubacteria, archaea
2
Q
When did the transition from prokaryotes to eukaryotes take place?
A
between 1.2 and 2 billion years ago.
3
Q
Describe organisms found in Kingdom Protista
A
- Very heterogeneous group
- Remained at eukaryotic, unicellular level of organization
- Evolved along numerous lines through specialization of
- cellular organelles (many unique) and/or • theskeleton(test)
- Simplicity and complexity reflected in number and nature of organelles and skeletons
- Compare: multicellular animals (tissues and organs)
- Occur wherever moisture is present (sea, freshwater, soil)
- Most are free-living
- Many are commensal, parasitic, or even mutualistic
- Solitary or colonial forms
- Microscopic to visible
4
Q
What does protozoa mean?
A
Animal like protist
5
Q
What are the types of animal like protist?
A
Amoeboid protozoa, Flagellated protozoa, Ciliated protozoa, Spore-forming protozoa
6
Q
What are the different types/phylum of amoeboid like protozoa?
A
- Phylum Rhizopoda- ‘Naked’amoebae • ‘Shelled’ amoebae
- Phylum Granuloreticulosa - Foraminiferans a.k.a. “forams”
- Phylum Actinopoda
7
Q
What are the types of Rhizopoda?
A
Naked amoebae and Shelled amoebae
8
Q
Describe the naked amoebae?
A
- E.g. Amoeba spp. live in sea, freshwater, moist soil
- Size range – few μm to several mm
- Cytoplasm divided - Stiff, outer ectoplasm (contracted proteins) • Fluid, inner endoplasm (relaxed proteins)
- Nucleus, food vacuoles, contractile vacuoles, Golgi complex, endoplasmic reticulum, etc. also present (few mitochondria)
9
Q
What are the two types of pseudopodia in naked amoeba?
A
• Lobopodia (seen in most amoebae) - wide round / blunted tips; tubular; ecto- and endoplasm; feeding and locomotion
• Filopodia (seen in small amoebae) • pointedends;composedof
ectoplasm only
1. Axopodia - locomotion only
2. Reticulopodia – feeding and locomotion
10
Q
Describe shelled amoeba?
A
- Inhabit freshwater, damp soil, moss • Shell (or test) is either
- secreted by ectoplasm (chitinoid/silaceous) e.g. Arcella sp.
- composed of foreign materials embedded in a (secreted) cementing matrix e.g. Difflugia sp.
- Amoeba attached to inner wall of shell
- Pseudopodia protrude through hole in shell
11
Q
Describe Phylum Granuloreticulosa
A
- “Forams” exist in great numbers at sea bottom
- Few μm – several mm in size (Numulites 50myo; 19cm!)
- Posses shells of CaCO3 (sometimes with sand reinforcement) • Contribute to chalk formation e.g. Cliffs of Dover, UK
- Ectoplasm extends over outside of shell (c.f. shelled amoebae) • Single chambered – unilocular
- Multichambered – multilocular
- Chambers added as animal grows
- Reticulopodia (nets) assist with food capture (diatoms, bacteria, etc) • Extracorporeal digestion followed by internal digestion
- Majority exist as fossils e.g. Elphidium crispum
12
Q
What are the classes of Actinopoda?
A
Radiolaria (marine) and Heliozoa (freshwater)
13
Q
Describe Phylum Actinopoda?
A
Pseudopodia - as axopodia – pseudopodia linked internally with microtubules (axoneme)
Inorganic endoskeleton - 1. radiating spicules of strontium sulphate on some species 2. spherical shell of silica which may also have radiating elements 3. Some are naked
14
Q
Explain locomotion in amoebae?
A
• Best developed in naked amoebae
• Flowing movement allowed for by
pseudopodia (three types)
•“Front-contraction” theory - At anterior end: endoplasmic proteins undergo contraction to form ectoplasm. At posterior end: ectoplasm is liquified during change to endoplasm
• Animal is pulled forward by contraction at anterior end
• Sticky surface on base of pseudopod
15
Q
Explain feeding and nutrition in amoeba?
A
Entirely holozoic (feeding like an animal– eating other organisms or their products)
• Phagocytosis - 1. Lobopodia extend around prey(e.g.
bacterium) in a cup-like fashion 2. Intracellular digestion follows (GERL) 3. Residual vacuole contents exocytosed
• Pinocytosis - Ingestion of dissolved nutrients
(aminoacids, monosaccharides, etc.)
• Extracorporealdigestion - 1. Involves hydrolytic enzymes followed by phagocytosis/ pinocytosis of products 2. Seen in parasitic species e.g. Entamoeba histolytica
16
Q
how does reproduction take place in amoebae?
A
- Mostly asexual (binary fission)
- Sexual: hologamy – fusion followed by detachment of two amoebae (genetic exchange?)
- Metagenesis – “Alternation of generations”
17
Q
How does reproduction take place in shelled amoebae?
A
- Soft shells divide into two parts
* New hard shells are secreted/deposited on bud
18
Q
How does reproduction take place in foraminifera?
A
- Budding
* Metagenesis
19
Q
How does reproduction take place in actinopoda?
A
- binary fission
* Biflagellate ‘swarmers’
20
Q
Name the different phylum found in flagellated protozoa
A
• Phylum Metamonada • Phylum Kinetoplastida • Phylum Opalinata
21
Q
what is the class under Granuloreticulosa
A
“foraminifera” (having chambers) aka forams
22
Q
describe the phylum metamonada
A
• Zooflagellates with few to many flagella
• These are commensals or parasites in the guts of
animals
• Lost mitochrondria secondarily
• retain nuclear genes derived from them
• mitochondrial relics include hydrogenosomes, which produce hydrogen, and small structures called mitosomes (contain mito-proteins)
23
Q
What are the classes of the phylum matamonada?
A
Diplomonada and Parabasalia
24
Q
Describe the class parabasalia
A
- An example from this class is Trichonympha sp.
- Lives in the hindgut of termites (insect)
- They have no mitochondria and have a symbiotic relationship with the termites as they breakdown the cellulose in the wood and plant fibres that are eaten by these termites.
25
why is multicellularity important?
Multicellular organisms thus have the competitive advantages of an increase in size without its limitations. They can have longer lifespans as they can continue living when individual cells die. Multicellularity also permits increasing complexity by allowing differentiation of cell types within one organism.
26
What is cellularisation theory?
a multinucleate protist could evolve internal membrane partitions around each of its nuclei, confining its sphere of operation to a certain region of the body, and thereby become internally compartmented
27
What is the symbiotic theory?
different types of protist could together symbiotically form a composite multicellular organism, similarly to the manner thought likely to be the origin of the eukaryote cell from different prokaryotes, and of lichens by algal and fungal partners
28
What is the colonial theory?
the asexual division products of a single individual protist could remain together after fission, and multicellularity arise via an intermediate colonial stage
29
Describe kingdom fungi
Eukaryotic, multicellular, heterotrophic organisms with cell walls made of chitin and that reproduce via spores.
• Body (mycelium) made up of an interwoven mass of threadlike filaments (hyphae) that are one cell thick.
• E.g. Mushrooms, rusts, smuts, puffballs, truffles, morels, molds and yeasts.
30
list characteristics of fungi
1. Eukaryotic (membrane bound nuclei ...............)
2. Body composed of thread-like hyphae (one-cell thick) which form an interwoven mass called a mycelium. Temporary reproductive structures (e.g. mushrooms) extend from the body (mycelium)
3. Heterotrophic- release extracellular enzymes and feed by absorption (break down nutrients stored in bodies or waste of other organisms- living or dead)
4. Almost every biological material can be broken down by at least one fungal species.
5. One predatory feeding on tiny worms in soil.
6.Non-photosynthetic, non-motile- filaments grow rapidly in any direction.
7. Chitin in cell walls (n-acetyl glucosamine units)
8. Absence of motile cells at any stage of life cycle but
choanoflagellate ancestry similar to that of animals.
9. Capable of sexual and asexual reproduction. Reproduce asexually under most conditions
10. Do not form embryos – form spores small and light and numerous (giant puffball contains 5 trillion spores)
31
What features do fungi share with animals?
No chloroplast.
heterotrophic organisms.
Require pre-formed organic compounds as energy sources.
Produce storage compounds, including glycogen, which is also found in animals.
32
What features does fungi share with plants?
possess a cell wall and vacuoles.
they reproduce both sexually and asexually.
they usually have haploid nuclei.
33
Unique features of fungi
* The fungal cell wall is composed of glucans and chitin; while the former compounds are also found in plants and the latter in the exoskeleton of arthropods
* Fungi are the only organisms that combine these two structural molecules in their cell wall.
* Unique body form-hyphae and mycelium
* Primary decomposers
* In contrast to plants fungal cell walls do not contain cellulose.
34
What are the importances of fungi?
Primary decomposers
provide antibiotics.
can be eaten by humans.
Fungi + plant root association (mycorrhizae) help make nutrients and water available to the roots.
35
what are the Lower and Higher fungi?
Lower Fungi:
Phylum: Chytridiomycota - Various species on spathodea seed wings
Phylum: Zygomycota - Rhizopus or Mucor
Phylum: Oomycota - Photographs of Phytophthora or Pythium showing the lemon shaped or globose sporangia, respectively
Higher Fungi:
Phylum: Ascomycota - Sordaria or slides of Erysiphe. In boht, the asci are within fruiting bodies.
Phylum: Basidiomycota - Mushrooms and/or bracket fungi
Nonsexual Fungi - Aspergillus, Penicillium, or Saccharomyces cerevisiae (baker's yeast)
36
Describe Kingdom Animalia.
Multicellular, heterotrophic, motile with a blastula stage in embryonic development
37
What are the characteristics of animals?
1. Animals are multicellular
2. Animals are heterotrophs - Ingest food and digest it in a central cavity (except for sponges).
3. Animal cells lack cell walls
4. Animals have a period of embryonic development- Progresses from blastula – gastrula – germ layers – tissues (cells become specialized as tissues form)
5. Animals are motile
6. Animals have nervous and muscle tissue
7. Animals are diploid (diplontic life cycle) - Their gametes are heterogametes (different sizes); eggs larger than sperm. Gametes are produced by meiosis
8. Most animals are symmetrical
9. Most Animals possess a body cavity (embryonic) - A fluid filled space (coelom)...If none (acoelus)
10. Many animals have a mouth and intestine
38
What is Basal lamina?
is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. (layer of extracellular proteins) supports the cells ≡ Tissues.
39
What are the types of symmetry?
Radial, Bilateral, Asymmetry
40
Describe radial symmetry
The body parts -arranged around a central axis
The animal can be cut along the axis in more than one plane to produce identical halves.
Animals tend to be sessile or sessile pelagic (e.g. jelly fishes)
Radial symmetry allows them to reach out in all directions.
41
Describe bilateral symmetry
Only one cut along the longitudinal axis will produce identical halves.
Bilateral symmetry is best for motile animals.
42
Describe asymmetry
Asymmetrical animals have no pattern of symmetry.
| The simplest animals? (sponges) are asymmetrical.
43
Which metazoan groups have certain types of symmetry?
Bilateral Symmetry - flatworms, round worms, protostomes, deuterosomes, mollusks, anthropoids, annelids, echinoderms, chordates,
Radial symmetry - cnidarians
asymmetry - sponges
44
What is extracellular digestion?
The gut - enables the animal to digest food outside of the cells
45
What is intracellular digestion?
In animals without a digestive tract, food items are brought into the cell for digestion
46
What are the different types of guts?
A sac-like gut - one opening. Food enters and leaves through the same opening
A complete gut - two openings, a mouth and an anus
47
What is the purpose of a gut?
A gut- allows for the specialization of parts along the tube E.g. food storage, secreting digestive enzymes, absorbing nutrients
48
Which metazoan groups have certain types of guts?
Complete gut - flatworms, round worms, protostomes, deuterosomes, mollusks, anthropoids, annelids, echinoderms, chordates,
Sac-like gut - flatworms, cnidarians
49
What are the different embryonic germ layers?
Ectoderm - Surface epithelia (skin) and nervous system
Mesoderm - Muscles, connective tissues (incl. blood), skeleton, kidneys, circulatory
and reproductive organs
Endoderm - Gives rise to the intestine and associated organs
50
What does diploblastic mean?
having two germ layers
51
What does triploblastic mean?
Having three germ layers
52
what is the body cavity?
A body cavity is any space or compartment, or potential space in the animal body. Cavities accommodate organs and other structures; cavities as potential spaces contain fluid.
53
what is the function of the body cavity?
Hydrostatic skeleton
Site for temporary accumulation of excess fluids, waste (2o circulatory system)
Site for maturation of eggs and sperm
Site allowing enlargement of internal organs
( e.g. gonads)
54
what does acoelomate mean?
An acoelomate is an animal that does not possess a body cavity.(solid mesoderm) e.g.- flatworms
55
what is haemocoel?
the primary body cavity of most invertebrates, containing circulatory fluid.
56
What is a pseudocoelomate?
A pseudocoelomate is an organism with body cavity that is not derived from the mesoderm, as in a true coelom, or body cavity. A pseudocoelomate is also known as a blastocoelomate, as the body cavity is derived from the blastocoel, or cavity within the embryo. Body cavity, fluid-filled, between the mesoderm and endoderm. e.g. nematodes (roundworms)
57
what is coelomate?
any animal possessing a fluid-filled cavity within which the digestive system is suspended. occurs entirely in the mesoderm e.g annelids, echinoderms and chordates
58
Which metazoan groups have certain types of embryonic germ layers?
1. 3 layers (triploblastic) coelomate - protostomes, deuterosomes, mollusks, anthropoids, annelids, echinoderms, chordates,
2. 3 layers (triploblastic) pseudocoelomate - roundworms
3. triploblastic acoelomate - flatworms
4. diploblastic (two layers) acoelomate - Cnidarians
5. multicell no tissues - sponges
59
Whats the difference in embryonic development between protostomes and deuterostomes?
protostomes are animals in which the first opening that appears in the embryo ( blastopore) is the mouth (1st mouth) while in deuterostome the first opening is the anus (2nd mouth)
60
describe embryonic development
fertilised animal egg divides to produce a solid ball of cells (morula). cell migration results in a hollow ball (blastula). cells near one end of the blastula migrate inward - gastrula. opening is the blastopore. tube produced by this process will become the gut. in species that have a separate mouth and anus the tube will eventually extend through the length of the embryo and fuse with the opposite side. one opening will become the mouth the other will become the anus
61
what sub-kingdom and phylum are sponges?
sub-kingdom - parazoa (beside animals)
| phylum - Porifera
62
describe the external features of Porifera (sponges)
```
tubular, encrusting, fingerlike.
Brightly coloured (live sponges in aquarium)
Body covered in pores- Porifera= pore bearer
```
63
What are the different body types of Porifera?
Asconoid Syconoid Leuconoid
64
What is Spongocoel/ atrium?
is the large, central cavity of sponges. Water enters the spongocoel through hundreds of tiny pores (ostia) and exits through the larger opening (osculum).
65
Describe the different sponge body types
Asconoid - Large reservoir of water. Small SA:V ratio. Inefficient use of
water. Restricted to smaller size classes
Syconoid - Larger SA:V ratio. More efficient use
of water. Still relatively small size classes
Leuconoid - Large SA:V ratio. Most efficient use
of water. Most sponges are of this type. Encrusting to large, goblet varieties
66
describe porifera skeletal structure
Body supported by a skeleton composed of spicules (hard mineralised) and collagen/protein fibres (spongin).
67
what are archaeocytes?
1. Totipotent 2. Phagocytic 3. Secretory (spicules and spongin
these are specialised cells that secrete picules (hard mineralised) and collagen/protein fibres (spongin).
68
What are the different types of spicules?
calcareous spicules.
siliceous demosponge spicules.
siliceous hexactine spicules.
69
What are the different cell types found in sponges?
Pinacocytes. Porocytes. Choanocytes. Archaeocytes.
70
What are Choanocytes?
Collar cells lining the inner walls of the body- responsible for pulling water into the sponge.
71
How do collar cells work?
beating of flagellum pulls water through the collar and away from the cell body.
72
What are Porocytes?
tubular cells forming the intake pores
73
What are pinococytes?
flattened cells that form the dermal layer – Pinacoderm (line the outer layer of the body)
74
How do sponges feed?
Bacteria and other very small particles trapped on
the collar of the choanocyte.
Filter – collar microvilli (0.1 um apart).
Cells engulf particles + other cells along the channels (amoebocyets)- intracellular digestion
One small group of sponges considered carnivorous- animals pulled in via water current.
75
describe sponges nervous system
Sponges have no nervous system
Local reactions
Coordination by transmission of messenger substances (chemicals like hormones)
Wandering ameboid cells
Fixed cells in contact with each other- no junctions
Defense: sponges produce biochemicals (toxic to fish, kill competitors, rash in humans- Red Caribbean fire sponge Tedania sp.)
76
List animal characteristics
1. multicellular
2. heterotrophic
3. embryonic development (blastula)
4. no cell walls (possess skeletal structures)
5. motile
6. nervous and muscle tissue
7. symmetrical
8. body cavity present
9. possess a gut
10. diploid
77
describe the sub-kingdom metazoa
1. tissues - basal lamina
2. grouped to form organs
3. definite mouth and anus (digestive system)
4. definite symmetry
5. layer and structures of the body derived from germ layers
6. embryonic development progresses beyond morula and blastula. gastrula- germ layers
78
describe the phylum cnideria
multicellular, radial symmetry with tissues and organs and possessing a "gastro/vascular" cavity or gut. no other body cavity. most cnideria live in shallow water and most are marine. includes hydras, jellyfish, sea anemones and corals.
79
What is the function nematocysts?
These are located throughout the epidermis. they are used for defence and prey capture. they can be toxic or non-toxic.
80
describe support in cnideria
soft bodied (jellyfish etc)- mesoglea
hydrozoans often have periderm of chitin over the epidermis
corals secret calcareous material
81
describe locomotion in cnideria
hydra sessile - can somersault or show inch worm like movement
jellyfish swim - contracting muscles of the umbrella margin and general surface.
82
What is the gastrovascular cavity?
enzymes reduce food to a broth - mixed by beating flagella in cavity.
83
What cnideria are exceptions to the carnivorous feeding?
aurelia - particlate feeding
cassiopeia - symbionts
corals - symbionts
84
what is the gastrodermis?
The gastrodermis is the inner layer of cells that serves as a lining membrane of the gastrovascular cavity of Cnidarians
85
what is pedal lacerations?
in sea anemones is a mode of fission which involves the spreading of the pedal disk and the degradation of tissue between the margin of the pedal disk and the body column. This produces crescent-shaped fragments which then regenerate into fully formed polyps.
86
How does reproduction take place in cnidernia?
dioecious (opposite of hermaphrodites)
gonads may be epidermal or gastrodermal
free swimming planula larva is the characteristic first larval stage
asexual reproduction by budding, fission and pedal lacerations.
87
what is planula?
is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species
88
what is the life cycle of Aurelia?
spermatozoa released via gastrovascular cavity from gonad. pass out through mouth. fertilised - planula larva
planula settles - scyphistoma. asexual reproduction by budding. example alteration of generations
89
what is scyphistoma?
the fixed polyp-like stage in the life cycle of a jellyfish, which reproduces asexually by budding
90
describe bilateral animals
Remaining phyla are essentially bilaterally symmetrical correlated with motility
Both sides of the animal are identical – encounter new environment in same way
Anterior portion meets new environment - bears sense organs (Cephalization- head development)
Upper and lower surfaces differ – lower in contact with substratum (Dorsal vs. ventral epithelium)
1st bilateral animals (flatworms, roundworms, annelid worms) – Different architecture.
91
what is the Peritoneum?
The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom.
92
what is the mesentery?
The mesentery is an organ which surrounds the organs of the gut, and suspends them from the abdominal wall. The mesentery is made of mesoderm cells,
93
What are the characteristics of phylum Platyhelminthes (flatworms)?
Bilateral
Vermiform- “wormlike”
Elongated, bilateral animals reduced appendages-
Large numbers are parasitic
Important pathogens of humans and domestic animals.
Parasitic forms- Bodies severely modified.
Use non-parasitic members to give general features (Phylum characteristics) Non-parasitic, free-living form: Auricles (ear lobes), Ocelli- eye spots, pharynx
Range of sizes (2 mm or less to more than a meter long- some tapeworms are meters long)
Flattened, leaf-like, long and ribbon-like
94
what are Rhabdites in Platyhelminthes?
Defense/protection; disintegrate to form a slimy covering around the animal; most numerous on dorsal surface
95
How does Platyhelminthes (flatworms) move?
Mucous glands: located marginally; provide temporary sheet of mucous on which animal glides
Cilia “row” on mucous
Active swimming: From transverse waves of muscle contractions
96
what are the functions of the Platyhelminthes structure?
1. packing tissue support
2. facilitates diffusion of nutrients and oxygen around body
3. represents a source of undifferentiated cells (pluripotent) which can migrate to wounded areas to facilitate tissue regeneration.
97
describe nutrition in Platyhelminthes
Carnivores. Digestive system: mouth, pharynx (muscular and can be protruded) and intestine.
no anus; faeces voided through mouth.
central mouth opens anywhere along the ventral midline.
intestinal structure provides basis for classification- simple or branched intestines.
98
Describe circulation and respiration in platyhelminthes
no special respiration organs.
gaseous exchange; diffusion all over body.
no circulatory system: parenchymal system may facilitate transport of nutrients and oxygen to internal tissues.
shape and structure of body important in these respects (dorsoventral flattening and small size) this is because they absorb oxygen directly through their skin so their flat shape helps this.
99
How does excretion work in Platyhelminthes?
excretory system composed of fine ramifying tubes.
open on surface via pores.
proto-nephridia
flame cell type flagellated cell
located in blind - ending portions of the body
probably used more for osmoregulation rather than excretion.
excretory product ammonia
diffuses through body surface + pores on the outside.
100
what is protonephridia?
The nephridium is an invertebrate organ, found in pairs and performing a function similar to the vertebrate kidney. Nephridia remove metabolic wastes from an animal's body. Nephridia come in two basic categories: metanephridia and protonephridia. Protonephridia are a type of nephridia that occur in invertebrates, including the phyla Platyhelminthes, Nemertea, Rotifera, and Chordata (lancelets). Metanephridia are the other type of nephridia which occur in invertebrates, including the phyla Annelida, Arthropoda, and Mollusca.
101
what are flame cells?
A flame cell is a specialized excretory cell found in the simplest freshwater invertebrates, including flatworms, rotifers and nemerteans. Flame cells function like a kidney, removing waste materials. Bundles of flame cells are called protonephridia.
102
what is negative phototactic
A negative phototaxis is one in which the organism moves away from the light source as demonstrated by certain insects such as cockroaches.
103
what are statocyst?
a small organ of balance and orientation in some aquatic invertebrates,
104
what are rheoreceptors?
a receptor in that responds to water currents
105
what is an auricle?
a structure resembling an ear or ear lobe in plnarians.
106
What kind of reproduction does flatworms have?
asexual that occurs by fission. if spilt in half longitudinally will have two heads.
sexual -
107
what is Cuticle in phylum nematoda (roundworms)?
The nematode cuticle is an extremely flexible and resilient exoskeleton that permits locomotion via attachment to muscle, confers environmental protection and allows growth by molting
108
describe longitudinal muscle
Unique feature: Each muscle extends processes/fibers to connect to the dorsal or ventral nerve.
Rather than the nerve extending an axon to connect with the muscle
109
how does locomotion work in nematoda?
Via undulating waves of muscle contractions passing along the muscle fibres of the body wall
Antangonistic forces: Hydrostatic skeleton of pseudocoelomic fluid and the elasticity of the cuticle
Aqueous environment required; move on side
110
what is a opisthaptor?
the posterior and usually complex adhesive organ of a monogenetic trematode.
111
what are prohaptors?
that is used for feeding and attachment. It is not the primary attachment organ but can anchor the body while the opisthaptor is being repositioned.
112
what is a definite host vs indefinite host?
The definitive host refers to the organism wherein the parasite reaches its mature form. Thus, the parasite at this stage is typically capable of reproduction.
an organism that supports the immature or non-reproductive forms of a parasite.
113
advantages of a coelom
Hydrostatic skeleton – facilitating support & movement
(fluid has little metabolic demand)
Site for temporary accumulation and movement of
nutrients, waste, gasses (2o circulatory system) Space for maturation of eggs and sperm
Space allowing enlargement of internal organs
( e.g. gonads)
114
what is cephalisation?
Cephalization is an evolutionary trend in which, over many generations, the mouth, sense organs, and nerve ganglia become concentrated at the front end of an animal, producing a head region.
115
why is cephalisation reduced in earthworms?
the earthworm's nervous system is distributed throughout its segments along the central nerve cord,
116
describe the different kinds of annelid movement
1. Peristalsis: Alternate contraction of circular and longitudinal muscles + setae
2. Wriggling/Parapodial stepping: Setae or parapodia providing contact with the substrate.
• Circular muscles extend worm
• Longitudinal muscles shorten worm.
117
What are the different pigments of blood in annelids?
- haemoglobin (red)
- chlorocruorin (green)
- haemerythrin (pink/violet)
118
what is Enteronephric system?
of an excretory system. : discharging into the intestine (as in certain annelid worms)
119
what are Typhlosole?
A typhlosole is an internal fold of the intestine or intestine inner wall. increases the surface area for absorption of food & re-absorption of water.
120
what is Clitellum
The clitellum is a thick, saddle-like ring found in the epidermis (skin) of the worm, usually with a light-colored pigment. To form a cocoon for its eggs, the clitellum secretes a viscous fluid.
121
What is a radula?
The radula (/ˈrædjʊlə/; plural radulae or radulas) is an anatomical structure used by mollusks for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus.
122
what is a odontophore?
a cartilaginous projection in the mouth of a mollusc, on which the radula is supported.
123
what is Crystalline style?
A style, sometimes referred to as a crystalline style, is a rod made of glycoprotein located in the midgut of most bivalves and some gastropods which aids in extracellular digestion
124
what is Haemocyanin?
Haemocyanin (or hemocyanin) is a protein which transports oxygen in the bodies of some invertebrates.
125
what is Myoglobin?
Myoglobin is an iron- and oxygen-binding protein found in the skeletal muscle tissue of vertebrates
126
what is Osphradia?
The olfactory organ in certain molluscs, linked with the respiration organ. Its main function is to test incoming water for silt and other possible food particles.
127
what is a gonoduct?
Either of a pair of ducts, leading from a gonad to the exterior, through which gametes pass.
128
Adductor muscle function
The muscles are strong enough to close the valves of the shell when they contract, and they are what enable the animal to close its valves tightly when necessary, such as when the bivalve is exposed to the air by low water levels, or when it is attacked by a predator.
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what is operculum?
is a hard, plate-like, bony flap that covers the gills of a bony fish
