Anas Zoology

  (Image Source:  https://scopeblog.stanford.edu/2013/08/04/image-of-the-week-botryllus-organism/ ) The Urochordata also known as Tunicata is a part of Phylum Chordata. General Characteristics of Urochordates: They are marine and sedentary. Their body is enclosed in a test/tunica. Notochord is present in the tail region in larvae (hence urochordate) and disappears in adults. Alimentary canal is complete and are ciliary feeders. Respiration is through numerous gill slits (Stigmata) which opens into the ectoderm lined cavity, the atrium. They show open circulation. They have special corpuscles, vanadocytes (except in Herdmania ) to extract vanadium from sea water and store it in blood vessels. Dorsal tubular nerve chord appears only in larval stage, which in adults is replaced by a single dorsal ganglia. Sense organs are in the form of receptors. Excretion is by nephrocytes, pyloric gland or neural gland. Asexual reproduction is by budding. Mostly hermaphrodite. Their developmen...

INTEGUMENT: Vertebrate body is covered by a tough, three layered body wall consisting of outer integument, middle muscular layer, and inner coelomic epithelium. It displays important morphological and physiological variations between different vertebrate groups depending on their adaptations for various habitats and mode of life. However, being a protective covering the integument is basically similar in structure in all vertebrates. Histologically skin is made up of two distinct layers. Epidermis: Ectodermal, stratified squamous epithelium, made up of few to several layers of cells. These layers include: Stratum germinativum/stratum malpighi/ stratum cyclindricum: It is the the innermost layer, firmly attached with the dermis and is settled on the basement membrane . It is continuously growing layer which push the new cell layers towards surface. It gets nourishment from dermis. Stratum corneum: It is the outermost partially cornified layer consisting of dead cells. It is made up of p...

  Amoeba Amoeba always reproduce asexually. There are different ways of asexual reproduction in Amoeba and they are as follows: 1) Binary Fission: Parent Amoeba divides into two daughter amoebae in favorable conditions. This is known as binary fission. Different phases of mitosis are accompanied with changes in the shape of body. In prophase, body becomes spherical with numerous pseudopodia and nucleus show intranuclear spindle. Chromatids appear as duplicated chromosomes in the nucleus. In metaphase chromosome arrange at the equator. In anaphase daughter chromosomes move towards opposite poles. In telophase. pseudopodia assume normal shape, constriction appear in the middle. One of the daughter retain contractile vacuole and the other acquires new vacuole. Now the parent after binary fission starts living as two individuals which later on grow in size.  Binary Fission in Amoeba 2) Sporulation: Some species of Amoeba reproduce by sporulation. Sporulation begins with breakdown ...

  Golgi Complex / Golgi Apparatus Golgi apparatus is found in all types of eukaryotic cells except the mammalian RBCs. It is absent in prokaryotes. Golgi apparatus are small sacs which are responsible for transporting, modifying and packaging proteins and lipids. The golgi apparatus was discovered by Camillo Golgi in 1898. He discovered them in the nerve cells. Golgi apparatus has a system of outer flattened cisternae which appears as parallel membranes in the form of an ellipse.  There are two faces known as cis and trans face of golgi apparatus. The cis face lies near the rough endoplasmic reticulum and the trans face lies near to the cell membrane. Substances from the rough endoplasmic reticulum enter through the cis face for processing and they exit from the trans face in the form of smaller vesicles. Functions: Packaging center of cell. Proteins are processed and sorted for their transport. Lipid processing. Secretory proteins like hormones are packed into secretory vesic...

  Common Sandpiper ( Actitis hypoleucos ) Distribution: The common sandpiper breeds across most of temperate and subtropical Europe and Asia, and migrated to Africa, Southern Asia and Australia in winter. Identification: It has greyish-brown upperparts, white underparts, short dark yellowish legs and feet and a bill with a pale base and a dark tip. The adult is 18-25 cm long with a 32-35 cm wingspan.  Conservation Status: Least Concern (LC) Related Posts: White-Eared Bulbul:  https://anaszoology.blogspot.com/2022/08/white-eared-bulbul-blogpost-3.html Scarlet Skimmer:  https://anaszoology.blogspot.com/2022/08/scarlet-skimmer-blogpost-2.html

  Endoplasmic Reticulum (ER) Endoplasmic Reticulum (ER) is a system of sac like structures and tubes found in all eukaryotic cells. They are known as sarcoplasmic reticulum in skeletal muscles, Nissl granules in neurons and myeloid bodies in retinal pigment cells. They are absent in RBCs, eggs and embryonic cells. Endoplasmic Reticulum arise by evagination of nuclear membrane. Endoplasmic Reticulum have three parts: Cisternae: It is a sac like, parallel tubules having ribosomes on their surface. It is unbranched. Tubules: It is tube like, irregular, branched and without ribosome. Vesicles: They are round or spherical, without ribosomes Parts of Endoplasmic Reticulum . There are two types of endoplasmic reticulum  Rough Endoplasmic Reticulum (RER): They have ribosomes on their surface. The 60S unit of ribosomes are attached to the ER by means of a protein ribophorin I and ribophorin II. Number of cisternae and tubules are more. They are abundant near the nuclear membrane. ...

  Cytoplasm: Cytoplasm is the protoplasm present within the living cell, excluding nucleus. Cytoplasm is enclosed within cell membrane. Cytoplasm can be differentiated as: Cytoplasmic matrix / Cytosol / Hyaloplasm Cell inclusions Cell organelles Cytoplasmic Matrix: The Cytoplasmic matrix is the the gel like substance present in cytoplasm. It is more dense and viscous than the cytoplasmic fluid. Cytoplasmic matrix contains enzymes for synthesis of carbohydrates, fats, amino acids and proteins. Cell Inclusions: Cell inclusion are the non-living substances of cytoplasm. They may be in the form of reserve food, minerals, excretory and secretory products. Some of these are: 1) Starch grains: Exists as eccentric of concentric rings around proteinaceous hilum. It is stored in rhizomes, potato, rice, maize etc. Starch Grains around hilum 2) Fat droplets: They are present in animal cells in the form of adipocytes. Fat droplet in the cell 3) Glycogen granules: They are present in liver and m...