Question

name the excreatory structs in invertebrates and crustanceans.

Answer 1

Answer:

Explanation:

These are present in the Peripatus and are situated on the lateral side of the segmented body cavity. Numbers of these paired organs correspond to the number of the segments of the trunk.

Each nephridium consists of a terminal vesicle which opens to the exterior through one end and remains connected to a coiled loop with the other. This loop is known as nephridial canal and it opens inside the body cavity. Its internal lining is ciliated.

Excretory Organ # 2. Coxal Glands:

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These glands are present only in Arachnida and their structures and positions vary (see Table 18.18—Arthropoda). Each coxal gland consists of convoluted tu­bules, called labyrinth and a sac called laby­rinth sac. It opens externally by a short tube.

Excretory structures of a few arthropods

Structure and position of coxal glands in arachnids

Excretory Organ # 3. Green Gland:

It is also known as the antennal gland or maxillary gland. In some species, the organs are also called green gland or antennal gland because of their colour and location (e.g., Astacus). In some freshwater crustacean species, the organs are situated near the maxillary segments and are called maxillary glands.

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It is found in Malacostraca (excepting Isopods) and larval forms of all Crustaceans, specially in Entomostracan larvae. It is present in the proximal segment of the second antenna or adjoining regions of the head. Each gland has three parts—end sac, labyrinth and bladder. The labyrinth is the proper excretory gland.

Excretory Organ # 4. Shell Glands:

These glands are also known as maxillary glands and are present in the coxopodites of second maxillae in Branchiopoda, Ostracoda, Copepoda, Cirripedia and larval forms of all Crusta­ceans.

Excretory Organ # 5. Malpighian Tubules:

These are long filamentous bodies with or without lumen and are made up of ciliated or cubical epithe­lium. These tubules usually originate from the region of the gut which denotes the beginning of hindgut. Among the Crusta­ceans, the Amphipods possess one pair of tubules which originate as diverticula of the alimentary canal.

In Insecta these develop from the undifferentiated region between the midgut and hindgut and the number varies from 2 to 150. Malpighian tubules occur in all insects except in Collembola, some of the Thysanura and the Aphids. The tubules often occur in two’s or multiples of two.