Choose the correct word to complete the sentences.

to identify pumps ink excretory three chambers feeding surrounded

 

Squid have …...... hearts. Two branchial hearts, …....... the gills, each surrounding the larger systemic heart that …....... blood around the body. The hearts have a faint greenish appearance and are …........ by the renal sacs – the main …....... system of the squid. The kidneys are faint and difficult …....... and stretch from the hearts (located at the posterior side of the…........ sac) to the liver. The systemic heart is made of three…....... , a lower ventricle and two upper auricles.

Working with word combinations and sentences

Give English equivalents to the following word combinations.

Многоклеточное животное, различные сообщества, единственная особенность, отсутствие позвоночника, вымершие формы, пресная вода, отличительные черты, жизненно-важные органы, пищеварительный тракт, внутренности, заключенный в полости, сложный мозг, предназначенные для сокращения мышцы, сильный клюв, слюнные железы, задний отдел, замечательное разнообразие, приспособление для маскировки, прямой контакт, прикрепить к телу, захватить добычу, способность менять цвета, многочисленные хроматофоры, плотная группа, участок кожи.

 

Match the beginning and the ending of the sentences.

	The vampire squid can emit luminescence for longer than two minutes as a result	a	which is usually followed by an escape response.
	The arm tip organs can also emit luminescence (glowing or flashing)	b	by the arm tip organs or an undiscovered visceral organ and can glow for up to 9.5 minutes.
	The third and final form of luminescence are luminescent clouds which appear	c	of the photophores which either glow simultaneously, flash one to three times per second, or pulsate.
	The particles are thought to be released	d	a mucous matrix with glowing particles in it.

 

Match each part of the eye structure to its definition and its context.

part	definition	context
pupil	The light-sensitive membrane that lines the back wall of the eyeball and is composed of several layers, including one containing the rods and cones.	The structure of.................... in the eyes of owls gives these nocturnal birds of prey excellent night vision.
reflection	The elongated cells or elements of the sensory layer of the retina, some of which are cylindrical, others somewhat conical	Our............ tend to contract in bright light and dilate in the dark.
retina	The circular opening in the center of the pigmented iris of the eye, through which light passes to the retina	As Shakespeare wrote, " The eye sees not itself, But by...............…."
rods and cones	The phenomenon of light or sound waves being thrown back from a surface; the act of reflecting, or turning or sending back	The................... receives an image formed by the lens and converts it into chemical and nervous signals that reach the brain by way of the optic nerve.

 

Translate the text into Russian.

The structure of the cephalopod eye

The cephalopod eye is probably the most sophisticated eye of all invertebrates and is as complex as the vertebrate eye, though the two are not homologous. For their body size, cephalopod eyes are relatively large. They contain an iris, pupil, and lens, but not necessarily a cornea. Octopuses are the only cephalopods with a completely protected " closed" cornea. That means that the eyes of squids and cuttlefish are in direct contact with sea water! The pupil in cephalopods is unique in that its morphology is different in octopuses, cuttlefish, and squid. Octopuses have a slit-shaped rectangular pupil. In cuttlefish it is W-shaped, and in squids it is round.

 

 

Working with texts

Read and translate the text.

Text 1

Invertebrates

A

A variety of otherwise unrelated groups of animals are lumped together by scientists as invertebrates. The only trait that distinguishes invertebrates from vertebrates, or animals with backbones, is the absence or presence of a backbone.

B

More than two dozen phyla of living invertebrates, plus many extinct forms, are recognized. Some of the largest and most important phyla of invertebrates are Sponges; Jellyfishes and Sea Anemones; Flatworms, Rotifers, Horsehair Worms, and Roundworms; Mollusks (snails, bivalves, squids, and octopuses), Annelida (segmented worms), Arthropoda (horseshoe crabs, spiders, crabs, centipedes, millipedes, and insects), and Echinodermata (starfishes and sea urchins).

C

The large group of animals called mollusks live on land and in both fresh and salt water. They constitute the phylum Mollusca, a major group of animals known to have as many as 100, 000 living species and more than 50, 000 fossil forms. Most mollusks, including snails, clams, oysters, and mussels, have shells. A major group called the cephalopods, however, including octopuses, squids, and cuttlefish, have shells that are either greatly diminished or absent. One of the most distinctive anatomical features characteristic of mollusks is a true coelom, a body cavity that contains most of the vital organs. The digestive tract, heart, liver, and reproductive organs are all housed inside the coelom.

Two other features that are characteristic of the mollusks and absent in most other groups of animals are the visceral mass and the mantle. The visceral mass is the main body of the animal and contains all the vital organs. The mantle is a thick covering of tissue that surrounds the visceral mass and has glands that secrete the shell, if the animal has one. Many of the aquatic mollusks also have another distinctive feature—gills that are enclosed within a cavity formed by the mantle.

D

Cephalopoda is the most morphologically and behaviorally complex class in the phylum Mollusca. Cephalopoda means " head foot" and this group has the most complex brain of any invertebrate. Cephalopods are characterized by a completely merged head and foot, with a ring of arms and/or tentacles surrounding the head. The mantle surrounds the visceral sac and possesses strong muscles required for contraction of the cavity and respiration.

Cephalopods are the most intelligent, most mobile, and the largest of all molluscs. Squid, octopuses, cuttlefish, the chambered nautilus, and their relatives display remarkable diversity in size and lifestyle with adaptations for predation, locomotion, disguise, and communication. Today, biologists and paleontologists continue to captivate the human mind and imagination with details of these molluscs' behavior, natural history, and evolution.

E

Arms and tentacles are another distinguishing cephalopod characteristic. All cephalopods have arms, but not all cephalopods have tentacles. Octopuses, cuttlefish, and squid have eight non-retractable arms, but only cuttlefish and squid have tentacles (two each). Arms usually have palps, often suckers, and sometimes hooks along their undersides. These can be attached to the arm directly or by a flexible stalk and are used to adhere to substrates and catch prey. Tentacles are longer than arms, are retractable, and usually have a blade-shaped or flattened tip, which is covered in suckers.

F

Cephalopods have an amazing ability to change color very rapidly. They accomplish this feat using numerous pigment-filled bags, called chromatophores. Chromatophores are found in the skin, and expand and contract to reveal or conceal small dots of color. They can be so densely concentrated that 200 may be found in a patch of skin the size of a pencil eraser.

 

Give a title to each paragraph.

 

A
B
C
D
E
F

 

Answer these questions to Text 1.

1. What phyla of invertebrates do you know?

2. What features distinguish mollusks from other invertebrates?

3. Tell about morphological characteristics of Cephalopods.

4. Describe the structure of Cephalopods.

5. Why and how do they change color?

6. What is the difference between arms and tentacles?

7. Tell about invertebrates` importance to humans.

 

Read the texts using your dictionary.

Retell one of the texts.

Text 2

Jelly Fish

The jellyfish is one of the oldest living creatures in the world. Jellyfish have existed on the face of this planet for over 650 million years. There are over 2000 species of jellyfish known in the world, with many more species being discovered as man searches the depths of the ocean. Jellyfish are a member of the phylum Cnidaria, to which the coral, sea whip and sea anemones also belong. They are simple invertebrates and are mobile unlike all other members of the phylum Cnidaria.

The perfectly symmetrical body of the jellyfish allows it to respond to danger from all sides. It also helps it in being able to detect food from every direction. The body of a jellyfish contains only a nervous system and the nerve receptors themselves formulate appropriate reaction to detection of light, odor, pressure and other external stimuli. The jellyfish does not have a brain or any specialized functional system. It has an outer layer (epidermis), and an inner layer (gastrodermis) which lines the gut. In between is the thick, elastic-like jelly known as mesoglea. In a simple digestive cavity the gullet, stomach and the intestine lie. There are four to eight oral arms near the mouth that help in bringing the food near the mouth, along with the tentacles. In fact, only 5% of the body of a jellyfish is solid matter.

Jellyfish have different shapes, sizes and colors. They can be smaller than an inch or larger than 7 feet in diameter, with tentacles spanning more than a 100 feet! Irrespective of their size, jellyfish can only have control over their vertical movement. Horizontally, their movement is completely controlled by the wind and the current. Their bell shape allows them to contract to get a push upwards. Jellyfish have the ability to sting with their tentacles. Their tentacles have a number of capsules that are filled with paralysis-causing toxins and are fired when the tentacles come in contact with something. Jellyfish use this facility mainly for hunting; however, jellyfish also use this facility to defend themselves. The toxins in the tentacles are powerful enough to paralyze their victim and buy enough time to escape, if not to kill it. However, in the case of humans, most jellyfish stings will only result in minor discomfort. The severity of stings is high in jellyfish found in warm and temperate oceans and these can be dangerous to humans.

While jellyfish do not actively attack humans, when their tentacles come in contact with human flesh, their stingers are released as part of their natural defense mechanism.

 

Text 3

Echinoderms

The phylum Echinodermata, which contains about 6000 species, gets its name from the Greek, literally meaning " spiny skin." Many echinoderms actually do have " spiny" skin, but others do not. This phylum exists exclusively in the sea, and cannot be found on land or in fresh water. All echinoderms have one thing in common: radial symmetry. This means that the creatures have appendages (or body construction) which point outward from the center of the body like the spokes on a bicycle wheel. Furthermore, these appendages usually occur in multiples of five, although there are a few exceptions. There are several well known members of this group, like sea stars and sea urchins. The radial symmetry is obvious in these creatures.

Perhaps not as obvious is the water vascular system, another trait common to all echinoderms. By examining the underside of a sea star, one will be able to see hundreds of tiny feet usually arranged into several rows on each ray (appendage) of the star. These are called tube feet, or podia, and are filled with sea water in most echinoderms. The vascular system within the body of the animal is also filled with sea water. By expanding and contracting chambers within the water vascular system, the echinoderm can force water into certain tube feet to extend them. The animal has muscles in the tube feet which are used to retract them. By expanding and retracting the right tube feet in the proper order, the creature can walk. Many echinoderms can also form suckers on the ends of their tube feet. These suckers can be used to capture and hold prey, or to hold onto rocks in a swift current or tide.

Interestingly, although most mature echinoderms live on the bottom, the larvae are usually planktonic with bilateral symmetry. During the process of maturing, the echinoderm will change its body shape from bilaterally symmetrical to radially symmetrical, and in the process, settle down on the sea floor.

Sea stars are capable of regenerating limbs in the event that one or more is damaged. The wound first closes off, and in time, the new limb will begin to grow. In a few species, the severed limb can regenerate a new sea star, but in most species, the severed limb dies. Sea stars eat a variety of different things, including clams, mussels, snails, sea urchins, and in some cases, other sea stars! Many sea stars, such as the Northern Sea Star, eat mussels and clams in a fascinating way. The sea star first surrounds its intended victim. Then it applies outward force (with its suction cup equipped tube feet) on the two mussel shells (called valves), to pull them apart. Contrary to popular belief, the sea star does not need to apply force for a long time in order to tire out the mussel. The sea star can apply so much force to the mussel valves (7 or more pounds! ) that it will bend the shell. Seizing the moment, the sea star then everts its stomach out through its mouth, and into the mussel (only a 1/100th of an inch opening is required). Once the sea star begins to digest its victim within the victim's own body, the victim dies. The sea star then finishes the meal by consuming the rest of the mussel. When the star is finished with the mussel, nothing remains but a shell.

 

 

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