Practical BIOS 02C4

Euglena

Image and video

https://www.youtube.com/watch?v=9nxoSRasq2Q

Characteristics

• Shape of cell maintained by pellicle

• Most with two flagella of unequal lengths for locomotion

• Single mitochondrion with discoidal cristae

• Photosynthetic forms have chlorophylls a and b.

• Thylakoid membranes arranged in stacks of three.

• Food reserves stored in cytoplasm as the unique starch paramylon

Noctiluca

Bioluminescence

https://www.youtube.com/watch?v=eTDxjOjzm9w

Characteristics

• Shape of cell maintained by pellicle consisting of alveolar vesicles beneath plasma membrane.

• With two flagella for locomotion: one transverse and one longitudinal

• Mitochondria with tubular cristae

• Nuclei with permanently condensed chromosomes

• Nuclear division without centrioles or MTOC

• Chloroplasts with thylakoids in stacks of 3

• Unique system of pusules for osmoregulation, excretion or buoyancy regulation

Paramecium

Image and video

https://www.youtube.com/watch?v=mh7KOtQTXrw

Characteristics

• Shape of cell maintained by pellicle consisting of alveolar vesicles and fibrous layer of epiplasm beneath plasma membrane

• Cilia for locomotion

• With two distinct types of nuclei: a hyperpolyploid macronucleus and a diploid micronucleus

• Without plastids

• Carbohydrates stored as glycogen

• Asexual reproduction by binary fission and sexual reproduction by conjugation

Sycon

Characteristics

• Metazoa with cellular grade construction, without true tissues

• With flagellated cells, choanocytes, that drives water through canals. Nuclei apical. Flagellum originates from nuclei

• Adults are sessile suspension feeders, larval stages are motile (partly flagellated amphiblastulae

• Skeletal elements, when present, composed on calcium carbonate

• Spicules ususally 1, 3 or 4 rayed

Cnidaria

Characteristics

• Diploblastic metazoa with ectoderm and endoderm separated by a ectodermally derived acellular mesoglea or partly cellular mesenchyme

• Primarily radially symmetrical body plan

• Presence of unique stinging or adhesive structures called cnidae

• Exhibit asexual polypoid and sexual medusoid variation

• Only one gastrovascular cavity named coelenteron

• Nervous system is simple nerve nets

Physalia

Characteristics

• Polymorphic floating colonies

• Attached distinct types of polyps and modified medusa

• Gas filled flotation zooids

Tubipora

Characteristics

• Simple polyps arise separately from ribbon-like stolon that forms an encrusting sheet or network

• Oral disc and tentacles retractable into anthostele

• Mesenchyme with sclerite

• Sclerites fuse to form calcareous skeleton

Metridium

Characteristics

• True coral, solitary or clonal but never colonial

• No calcareous skeleton lacking

• Oral tentacles conical

Taenia

Characteristics

• Exclusive endoparasite, can be very long (some over 10 meters)

• Body covered by tegument

• Triploblastic, acoelomate, bilaterally symmetrical, flattened dorsoventrally

• Cephalized with a central nervous system comprising of an anterior cerebral ganglion

• Body consists of an anterior scolex, short neck and then a strobili composed of a series of segments or proglotids

• First larval stage (onchosphere or hexacanth larva) with six hooks

• Lifecycle requires one or more intermediate hosts

Ascaris

Characteristics

• Triploblasitc, bilateral, vermiform, unsegmented, blastocoelomate

• Body round in cross section and covered by layered cuticle. Juveniles grow by shedding cuticles

• With cephalic sense organ called amphids

• Complete gut with radially symmetrical mouth parts

Nereis

Characteristics

• Bilaterally symmetrical, segmented worms

• Complete digestive tract

• Complete circulatory systems with

• Nervous system with dorsal cerebral ganglion, circumenteric connectives and ventral ganglionated nerve cord

• Numerous chaetae (setae) on trunk segments, most with developed parapodia

• Two antennae, two large appandages or palps and four pairs of tentacles are on head

• Free swimming trochophore larva